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Author SHA1 Message Date
Subhrodip Mohanta
b10b9c159e
Update abstract-factory/README.md 2021-06-05 12:50:40 +05:30
Ilkka Seppälä
0aaa5dab01
Grammatical fixes 2021-06-05 09:26:08 +03:00
520 changed files with 7586 additions and 18199 deletions

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@ -16,17 +16,6 @@
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@ -24,9 +24,6 @@
# This workflow will build a Java project with Maven
# For more information see: https://help.github.com/actions/language-and-framework-guides/building-and-testing-java-with-maven
# We are using two jobs here for testing our code on the latest JDK 11 build as well as a more satble build version of 11.0.3
# You can see the full discussion here https://github.com/iluwatar/java-design-patterns/pull/1868#issue-1029459688
name: Java CI
on:
@ -36,11 +33,10 @@ on:
jobs:
# This Workflow Job will build this project and run Sonar analysis using JDK 11.0.3
build-and-analyze:
build:
name: Build and Run Sonar analysis on JDK 11.0.3
runs-on: ubuntu-20.04
steps:
- name: Checkout Code
@ -49,14 +45,12 @@ jobs:
# Disabling shallow clone for improving relevancy of SonarQube reporting
fetch-depth: 0
- name: Set up JDK 11.0.3
- name: Set up JDK 11
uses: actions/setup-java@v2
with:
java-version: 11.0.3
distribution: 'zulu'
cache: 'maven'
java-version: 11
distribution: 'adopt'
# Cache Sonar packages which as used to run anaylysis and collect metrics
- name: Cache SonarCloud packages
uses: actions/cache@v2
with:
@ -64,6 +58,14 @@ jobs:
key: ${{ runner.os }}-sonar
restore-keys: ${{ runner.os }}-sonar
- name: Cache Maven dependencies
uses: actions/cache@v2
with:
path: ~/.m2/repository
key: ${{ runner.os }}-maven-${{ hashFiles('**/pom.xml') }}
restore-keys: |
${{ runner.os }}-maven-
# Some tests need screen access
- name: Install xvfb
run: sudo apt-get install -y xvfb
@ -74,28 +76,3 @@ jobs:
# These two env variables are needed for sonar analysis
GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
SONAR_TOKEN: ${{ secrets.SONAR_TOKEN }}
# This Workflow Job is going to build the project on the latest stable JDK 11
build:
name: Build and Test on JDK 11
runs-on: ubuntu-20.04
steps:
- name: Checkout Code
uses: actions/checkout@v2
- name: Set up JDK 11 (Latest)
uses: actions/setup-java@v2
with:
java-version: 11
distribution: 'zulu'
cache: 'maven'
# Some tests need screen access
- name: Install xvfb
run: sudo apt-get install -y xvfb
- name: Build with Maven
run: xvfb-run ./mvnw clean verify

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@ -34,22 +34,25 @@ on:
jobs:
build:
name: Build JDP
runs-on: ubuntu-20.04
strategy:
matrix:
java-version: [ 11.0.3, 11 ]
steps:
- name: Checkout Code
uses: actions/checkout@v2
- name: Set up JDK ${{ matrix.java-version }}
- name: Set up JDK 11
uses: actions/setup-java@v2
with:
java-version: ${{ matrix.java-version }}
distribution: 'zulu'
cache: 'maven'
java-version: 11
distribution: 'adopt'
- name: Cache Maven Dependecies
uses: actions/cache@v2
with:
path: ~/.m2/repository
key: ${{ runner.os }}-maven-${{ hashFiles('**/pom.xml') }}
restore-keys: |
${{ runner.os }}-maven-
# Some tests need screen access
- name: Install xvfb

1
.gitignore vendored
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@ -12,7 +12,6 @@ tmp/
local.properties
.loadpath
.recommenders
.DS_Store
####### Java annotation processor (APT) ########
.factorypath

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@ -1,18 +1,25 @@
# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements. See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership. The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied. See the License for the
# specific language governing permissions and limitations
# under the License.
distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.8.4/apache-maven-3.8.4-bin.zip
wrapperUrl=https://repo.maven.apache.org/maven2/org/apache/maven/wrapper/maven-wrapper/3.1.0/maven-wrapper-3.1.0.jar
#
# The MIT License
# Copyright © 2014-2021 Ilkka Seppälä
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
#
distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.6.3/apache-maven-3.6.3-bin.zip
wrapperUrl=https://repo.maven.apache.org/maven2/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar

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@ -1,6 +1,6 @@
The MIT License (MIT)
Copyright © 2014-2021 Ilkka Seppälä
Copyright (c) 2014-2021 Ilkka Seppälä
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
@ -19,6 +19,3 @@ AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
Module Model-view-viewmodel is using ZK framework
ZK framework is licensed under LGPL and the license can be found at lgpl-3.0.txt

146
README.md
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@ -10,18 +10,18 @@
[![Coverage](https://sonarcloud.io/api/project_badges/measure?project=iluwatar_java-design-patterns&metric=coverage)](https://sonarcloud.io/dashboard?id=iluwatar_java-design-patterns)
[![Join the chat at https://gitter.im/iluwatar/java-design-patterns](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/iluwatar/java-design-patterns?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
<!-- ALL-CONTRIBUTORS-BADGE:START - Do not remove or modify this section -->
[![All Contributors](https://img.shields.io/badge/all_contributors-198-orange.svg?style=flat-square)](#contributors-)
[![All Contributors](https://img.shields.io/badge/all_contributors-168-orange.svg?style=flat-square)](#contributors-)
<!-- ALL-CONTRIBUTORS-BADGE:END -->
<br/>
Read in different language : [**zh**](localization/zh/README.md), [**ko**](localization/ko/README.md), [**fr**](localization/fr/README.md), [**tr**](localization/tr/README.md), [**ar**](localization/ar/README.md), [**es**](localization/es/README.md), [**pt**](localization/pt/README.md), [**id**](localization/id/README.md), [**ru**](localization/ru/README.md), [**de**](localization/de/README.md), [**ja**](localization/ja/README.md)
Read in different language : [**zh**](/localization/zh/README.md), [**ko**](/localization/ko/README.md), [**fr**](/localization/fr/README.md), [**tr**](/localization/tr/README.md), [**ar**](/localization/ar/README.md), [**es**](/localization/es/README.md)
<br/>
# Introduction
Design patterns are the best, formalized practices a programmer can use to
Design patterns are the best formalized practices a programmer can use to
solve common problems when designing an application or system.
Design patterns can speed up the development process by providing tested, proven
@ -34,11 +34,11 @@ are familiar with the patterns.
# Getting started
This site showcases Java Design Patterns. The solutions have been developed by
experienced programmers and architects from the open-source community. The
patterns can be browsed by their high-level descriptions or by looking at their
source code. The source code examples are well commented and can be thought of as
experienced programmers and architects from the open source community. The
patterns can be browsed by their high level descriptions or by looking at their
source code. The source code examples are well commented and can be thought as
programming tutorials on how to implement a specific pattern. We use the most
popular battle-proven open-source Java technologies.
popular battle-proven open source Java technologies.
Before you dive into the material, you should be familiar with various
[Software Design Principles](https://java-design-patterns.com/principles/).
@ -56,8 +56,8 @@ of the following approaches
- Using tags such as `Performance`, `Gang of Four` or `Data access`.
- Using pattern categories, `Creational`, `Behavioral`, and others.
Hopefully, you find the object-oriented solutions presented on this site useful
in your architectures and have as much fun learning them as we had while developing them.
Hopefully you find the object oriented solutions presented on this site useful
in your architectures and have as much fun learning them as we had developing them.
# How to contribute
@ -77,26 +77,29 @@ This project is licensed under the terms of the MIT license.
<table>
<tr>
<td align="center"><a href="https://github.com/iluwatar"><img src="https://avatars1.githubusercontent.com/u/582346?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Ilkka Seppälä</b></sub></a><br /><a href="#projectManagement-iluwatar" title="Project Management">📆</a> <a href="#maintenance-iluwatar" title="Maintenance">🚧</a> <a href="#content-iluwatar" title="Content">🖋</a></td>
<td align="center"><a href="http://subho.xyz"><img src="https://avatars0.githubusercontent.com/u/13291222?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Subhrodip Mohanta</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ohbus" title="Code">💻</a> <a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3Aohbus" title="Reviewed Pull Requests">👀</a> <a href="#maintenance-ohbus" title="Maintenance">🚧</a></td>
<td align="center"><a href="https://github.com/amit1307"><img src="https://avatars0.githubusercontent.com/u/23420222?v=4?s=100" width="100px;" alt=""/><br /><sub><b>amit1307</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=amit1307" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/npathai"><img src="https://avatars2.githubusercontent.com/u/1792515?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Narendra Pathai</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=npathai" title="Code">💻</a> <a href="#ideas-npathai" title="Ideas, Planning, & Feedback">🤔</a> <a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3Anpathai" title="Reviewed Pull Requests">👀</a></td>
<td align="center"><a href="https://github.com/fluxw42"><img src="https://avatars1.githubusercontent.com/u/1545460?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Jeroen Meulemeester</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=fluxw42" title="Code">💻</a></td>
<td align="center"><a href="http://www.joemccarthy.co.uk"><img src="https://avatars0.githubusercontent.com/u/4526195?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Joseph McCarthy</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=mikulucky" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/thomasoss"><img src="https://avatars1.githubusercontent.com/u/22516154?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Thomas</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=thomasoss" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="http://www.joemccarthy.co.uk"><img src="https://avatars0.githubusercontent.com/u/4526195?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Joseph McCarthy</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=mikulucky" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/thomasoss"><img src="https://avatars1.githubusercontent.com/u/22516154?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Thomas</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=thomasoss" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/anuragagarwal561994"><img src="https://avatars1.githubusercontent.com/u/6075379?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Anurag Agarwal</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=anuragagarwal561994" title="Code">💻</a></td>
<td align="center"><a href="https://markusmo3.github.io"><img src="https://avatars1.githubusercontent.com/u/3317416?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Markus Moser</b></sub></a><br /><a href="#design-markusmo3" title="Design">🎨</a> <a href="https://github.com/iluwatar/java-design-patterns/commits?author=markusmo3" title="Code">💻</a> <a href="#ideas-markusmo3" title="Ideas, Planning, & Feedback">🤔</a></td>
</tr>
<tr>
<td align="center"><a href="https://twitter.com/i_sabiq"><img src="https://avatars1.githubusercontent.com/u/19510920?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Sabiq Ihab</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=isabiq" title="Code">💻</a></td>
<td align="center"><a href="http://inbravo.github.io"><img src="https://avatars3.githubusercontent.com/u/5253764?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Amit Dixit</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=inbravo" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/piyushchaudhari04"><img src="https://avatars3.githubusercontent.com/u/10268029?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Piyush Kailash Chaudhari</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=piyushchaudhari04" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/joshzambales"><img src="https://avatars1.githubusercontent.com/u/8704552?v=4?s=100" width="100px;" alt=""/><br /><sub><b>joshzambales</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=joshzambales" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/Crossy147"><img src="https://avatars2.githubusercontent.com/u/7272996?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Kamil Pietruszka</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Crossy147" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/Crossy147"><img src="https://avatars2.githubusercontent.com/u/7272996?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Kamil Pietruszka</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Crossy147" title="Code">💻</a></td>
<td align="center"><a href="http://cs.joensuu.fi/~zkhayda"><img src="https://avatars2.githubusercontent.com/u/660742?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Zafar Khaydarov</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=zafarella" title="Code">💻</a> <a href="https://github.com/iluwatar/java-design-patterns/commits?author=zafarella" title="Documentation">📖</a></td>
<td align="center"><a href="https://kemitix.github.io/"><img src="https://avatars1.githubusercontent.com/u/1147749?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Paul Campbell</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=kemitix" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/Argyro-Sioziou"><img src="https://avatars0.githubusercontent.com/u/22822639?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Argyro Sioziou</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Argyro-Sioziou" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/TylerMcConville"><img src="https://avatars0.githubusercontent.com/u/4946449?v=4?s=100" width="100px;" alt=""/><br /><sub><b>TylerMcConville</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=TylerMcConville" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/saksham93"><img src="https://avatars1.githubusercontent.com/u/37399540?v=4?s=100" width="100px;" alt=""/><br /><sub><b>saksham93</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=saksham93" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/nikhilbarar"><img src="https://avatars2.githubusercontent.com/u/37332144?v=4?s=100" width="100px;" alt=""/><br /><sub><b>nikhilbarar</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=nikhilbarar" title="Code">💻</a></td>
@ -107,32 +110,38 @@ This project is licensed under the terms of the MIT license.
<td align="center"><a href="https://github.com/JuhoKang"><img src="https://avatars1.githubusercontent.com/u/4745294?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Juho Kang</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=JuhoKang" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/dheeraj-mummareddy"><img src="https://avatars2.githubusercontent.com/u/7002230?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Dheeraj Mummareddy</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=dheeraj-mummareddy" title="Code">💻</a></td>
<td align="center"><a href="https://www.bernardosulzbach.com"><img src="https://avatars0.githubusercontent.com/u/8271090?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Bernardo Sulzbach</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=bernardosulzbach" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/4lexis"><img src="https://avatars0.githubusercontent.com/u/19871727?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Aleksandar Dudukovic</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=4lexis" title="Code">💻</a></td>
<td align="center"><a href="https://www.yusufaytas.com"><img src="https://avatars2.githubusercontent.com/u/1049483?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Yusuf Aytaş</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=yusufaytas" title="Code">💻</a></td>
<td align="center"><a href="http://futurehomes.hu"><img src="https://avatars2.githubusercontent.com/u/1001491?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Mihály Kuprivecz</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=qpi" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/kapinuss"><img src="https://avatars0.githubusercontent.com/u/17639945?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Stanislav Kapinus</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=kapinuss" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/kapinuss"><img src="https://avatars0.githubusercontent.com/u/17639945?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Stanislav Kapinus</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=kapinuss" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/gvsharma"><img src="https://avatars1.githubusercontent.com/u/6648152?v=4?s=100" width="100px;" alt=""/><br /><sub><b>GVSharma</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=gvsharma" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/SrdjanPaunovic"><img src="https://avatars1.githubusercontent.com/u/22815104?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Srđan Paunović</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=SrdjanPaunovic" title="Code">💻</a></td>
<td align="center"><a href="https://sideris.xyz/"><img src="https://avatars3.githubusercontent.com/u/5484694?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Petros G. Sideris</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=sideris" title="Code">💻</a></td>
<td align="center"><a href="https://www.linkedin.com/in/pramodgupta3/"><img src="https://avatars1.githubusercontent.com/u/2184241?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Pramod Gupta</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3AIAmPramod" title="Reviewed Pull Requests">👀</a></td>
<td align="center"><a href="https://amarnath510.github.io/portfolio"><img src="https://avatars0.githubusercontent.com/u/4599623?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Amarnath Chandana</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Amarnath510" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/Anurag870"><img src="https://avatars1.githubusercontent.com/u/6295975?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Anurag870</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Anurag870" title="Code">💻</a> <a href="https://github.com/iluwatar/java-design-patterns/commits?author=Anurag870" title="Documentation">📖</a></td>
</tr>
<tr>
<td align="center"><a href="https://amarnath510.github.io/portfolio"><img src="https://avatars0.githubusercontent.com/u/4599623?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Amarnath Chandana</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Amarnath510" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/Anurag870"><img src="https://avatars1.githubusercontent.com/u/6295975?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Anurag870</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Anurag870" title="Code">💻</a> <a href="https://github.com/iluwatar/java-design-patterns/commits?author=Anurag870" title="Documentation">📖</a></td>
<td align="center"><a href="http://theerroris.me"><img src="https://avatars0.githubusercontent.com/u/1685953?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Wes Gilleland</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Deathnerd" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/Harshrajsinh"><img src="https://avatars2.githubusercontent.com/u/22811531?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Harshraj Thakor</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Harshrajsinh" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/MaVdbussche"><img src="https://avatars1.githubusercontent.com/u/26136934?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Martin Vandenbussche</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=MaVdbussche" title="Code">💻</a></td>
<td align="center"><a href="https://alexsomai.com"><img src="https://avatars1.githubusercontent.com/u/5720977?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Alexandru Somai</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=alexsomai" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/amogozov"><img src="https://avatars3.githubusercontent.com/u/7372215?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Artur Mogozov</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=amogozov" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/anthonycampbell"><img src="https://avatars3.githubusercontent.com/u/10249255?v=4?s=100" width="100px;" alt=""/><br /><sub><b>anthony</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=anthonycampbell" title="Code">💻</a></td>
<td align="center"><a href="http://ccygnus.com/"><img src="https://avatars1.githubusercontent.com/u/9342724?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Christian Cygnus</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=christophercolumbusdog" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="http://ccygnus.com/"><img src="https://avatars1.githubusercontent.com/u/9342724?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Christian Cygnus</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=christophercolumbusdog" title="Code">💻</a></td>
<td align="center"><a href="https://about.me/dzmitryh"><img src="https://avatars2.githubusercontent.com/u/5390492?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Dima Gubin</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=dzmitryh" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/jjjimenez100"><img src="https://avatars3.githubusercontent.com/u/22243493?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Joshua Jimenez</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=jjjimenez100" title="Code">💻</a></td>
<td align="center"><a href="http://about.me/kaiwinter"><img src="https://avatars0.githubusercontent.com/u/110982?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Kai Winter</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=kaiwinter" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/lbroman"><img src="https://avatars1.githubusercontent.com/u/86007?v=4?s=100" width="100px;" alt=""/><br /><sub><b>lbroman</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=lbroman" title="Code">💻</a></td>
<td align="center"><a href="https://przemeknowak.com"><img src="https://avatars1.githubusercontent.com/u/3254609?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Przemek</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=pnowy" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/prafful1"><img src="https://avatars0.githubusercontent.com/u/14350274?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Prafful Agarwal</b></sub></a><br /><a href="#content-prafful1" title="Content">🖋</a></td>
@ -143,32 +152,38 @@ This project is licensed under the terms of the MIT license.
<td align="center"><a href="https://github.com/valdar-hu"><img src="https://avatars3.githubusercontent.com/u/17962817?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Krisztián Nagy</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=valdar-hu" title="Code">💻</a></td>
<td align="center"><a href="https://www.vanogrid.com"><img src="https://avatars0.githubusercontent.com/u/4307918?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Alexander Ivanov</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=vanogrid" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/yosfik"><img src="https://avatars3.githubusercontent.com/u/4850270?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Yosfik Alqadri</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=yosfik" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/7agustibm"><img src="https://avatars0.githubusercontent.com/u/8149332?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Agustí Becerra Milà</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=7agustibm" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/Juaanma"><img src="https://avatars3.githubusercontent.com/u/7390500?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Juan Manuel Suárez</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Juaanma" title="Code">💻</a></td>
<td align="center"><a href="http://www.devsedge.net/"><img src="https://avatars0.githubusercontent.com/u/9956006?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Luigi Cortese</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=LuigiCortese" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/Rzeposlaw"><img src="https://avatars2.githubusercontent.com/u/18425745?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Katarzyna Rzepecka</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Rzeposlaw" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/Rzeposlaw"><img src="https://avatars2.githubusercontent.com/u/18425745?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Katarzyna Rzepecka</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Rzeposlaw" title="Code">💻</a></td>
<td align="center"><a href="http://adamski.pro"><img src="https://avatars1.githubusercontent.com/u/6537430?v=4?s=100" width="100px;" alt=""/><br /><sub><b>adamski.pro</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=akrystian" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/baislsl"><img src="https://avatars0.githubusercontent.com/u/17060584?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Shengli Bai</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=baislsl" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/besok"><img src="https://avatars2.githubusercontent.com/u/29834592?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Boris</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=besok" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/dmitraver"><img src="https://avatars3.githubusercontent.com/u/1798156?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Dmitry Avershin</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=dmitraver" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/fanofxiaofeng"><img src="https://avatars0.githubusercontent.com/u/3983683?v=4?s=100" width="100px;" alt=""/><br /><sub><b>靳阳</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=fanofxiaofeng" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/hoangnam2261"><img src="https://avatars2.githubusercontent.com/u/31692990?v=4?s=100" width="100px;" alt=""/><br /><sub><b>hoangnam2261</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=hoangnam2261" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/fanofxiaofeng"><img src="https://avatars0.githubusercontent.com/u/3983683?v=4?s=100" width="100px;" alt=""/><br /><sub><b>靳阳</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=fanofxiaofeng" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/hoangnam2261"><img src="https://avatars2.githubusercontent.com/u/31692990?v=4?s=100" width="100px;" alt=""/><br /><sub><b>hoangnam2261</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=hoangnam2261" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/jarpit96"><img src="https://avatars2.githubusercontent.com/u/10098713?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Arpit Jain</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=jarpit96" title="Code">💻</a></td>
<td align="center"><a href="http://joningi.net"><img src="https://avatars2.githubusercontent.com/u/6115148?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Jón Ingi Sveinbjörnsson</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=joningiwork" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/kirill-vlasov"><img src="https://avatars3.githubusercontent.com/u/16112495?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Kirill Vlasov</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=kirill-vlasov" title="Code">💻</a></td>
<td align="center"><a href="http://mitchell-irvin.com"><img src="https://avatars0.githubusercontent.com/u/16233245?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Mitchell Irvin</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=mitchellirvin" title="Code">💻</a></td>
<td align="center"><a href="https://ranjeet-floyd.github.io"><img src="https://avatars0.githubusercontent.com/u/1992972?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Ranjeet</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ranjeet-floyd" title="Code">💻</a></td>
<td align="center"><a href="https://alwayswithme.github.io"><img src="https://avatars3.githubusercontent.com/u/3234786?v=4?s=100" width="100px;" alt=""/><br /><sub><b>PhoenixYip</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Alwayswithme" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/MSaifAsif"><img src="https://avatars1.githubusercontent.com/u/6280554?v=4?s=100" width="100px;" alt=""/><br /><sub><b>M Saif Asif</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=MSaifAsif" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/MSaifAsif"><img src="https://avatars1.githubusercontent.com/u/6280554?v=4?s=100" width="100px;" alt=""/><br /><sub><b>M Saif Asif</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=MSaifAsif" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/kanwarpreet25"><img src="https://avatars0.githubusercontent.com/u/39183641?v=4?s=100" width="100px;" alt=""/><br /><sub><b>kanwarpreet25</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=kanwarpreet25" title="Code">💻</a></td>
<td align="center"><a href="http://leonmak.me"><img src="https://avatars3.githubusercontent.com/u/13071508?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Leon Mak</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=leonmak" title="Code">💻</a></td>
<td align="center"><a href="http://www.wramdemark.se"><img src="https://avatars2.githubusercontent.com/u/7052193?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Per Wramdemark</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=perwramdemark" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/waisuan"><img src="https://avatars2.githubusercontent.com/u/10975700?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Evan Sia Wai Suan</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=waisuan" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/AnaghaSasikumar"><img src="https://avatars2.githubusercontent.com/u/42939261?v=4?s=100" width="100px;" alt=""/><br /><sub><b>AnaghaSasikumar</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=AnaghaSasikumar" title="Code">💻</a></td>
<td align="center"><a href="https://christofferh.com"><img src="https://avatars1.githubusercontent.com/u/767643?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Christoffer Hamberg</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=christofferh" title="Code">💻</a></td>
@ -179,32 +194,38 @@ This project is licensed under the terms of the MIT license.
<td align="center"><a href="https://github.com/leogtzr"><img src="https://avatars0.githubusercontent.com/u/1211969?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Leo Gutiérrez Ramírez</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=leogtzr" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/npczwh"><img src="https://avatars0.githubusercontent.com/u/14066422?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Zhang WH</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=npczwh" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/oconnelc"><img src="https://avatars0.githubusercontent.com/u/1112973?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Christopher O'Connell</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=oconnelc" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/giorgosmav21"><img src="https://avatars2.githubusercontent.com/u/22855493?v=4?s=100" width="100px;" alt=""/><br /><sub><b>George Mavroeidis</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=giorgosmav21" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/hbothra15"><img src="https://avatars1.githubusercontent.com/u/7418012?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Hemant Bothra</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=hbothra15" title="Code">💻</a> <a href="#design-hbothra15" title="Design">🎨</a></td>
<td align="center"><a href="https://www.kevinpeters.net/about/"><img src="https://avatars1.githubusercontent.com/u/12736734?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Kevin Peters</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=igeligel" title="Code">💻</a></td>
<td align="center"><a href="https://llorllale.github.io/"><img src="https://avatars1.githubusercontent.com/u/2019896?v=4?s=100" width="100px;" alt=""/><br /><sub><b>George Aristy</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=llorllale" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://llorllale.github.io/"><img src="https://avatars1.githubusercontent.com/u/2019896?v=4?s=100" width="100px;" alt=""/><br /><sub><b>George Aristy</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=llorllale" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/mookkiah"><img src="https://avatars1.githubusercontent.com/u/8975264?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Mahendran Mookkiah</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=mookkiah" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/Azureyjt"><img src="https://avatars2.githubusercontent.com/u/18476317?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Azureyjt</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Azureyjt" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/vehpsr"><img src="https://avatars2.githubusercontent.com/u/3133265?v=4?s=100" width="100px;" alt=""/><br /><sub><b>gans</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=vehpsr" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/ThatGuyWithTheHat"><img src="https://avatars0.githubusercontent.com/u/24470582?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Matt</b></sub></a><br /><a href="#content-ThatGuyWithTheHat" title="Content">🖋</a></td>
<td align="center"><a href="https://www.linkedin.com/in/gopinathlangote/"><img src="https://avatars2.githubusercontent.com/u/10210778?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Gopinath Langote</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=gopinath-langote" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/hoswey"><img src="https://avatars3.githubusercontent.com/u/3689445?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Hoswey</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=hoswey" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://www.linkedin.com/in/gopinathlangote/"><img src="https://avatars2.githubusercontent.com/u/10210778?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Gopinath Langote</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=gopinath-langote" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/hoswey"><img src="https://avatars3.githubusercontent.com/u/3689445?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Hoswey</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=hoswey" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/amit2103"><img src="https://avatars3.githubusercontent.com/u/7566692?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Amit Pandey</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=amit2103" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/gwildor28"><img src="https://avatars0.githubusercontent.com/u/16000365?v=4?s=100" width="100px;" alt=""/><br /><sub><b>gwildor28</b></sub></a><br /><a href="#content-gwildor28" title="Content">🖋</a></td>
</tr>
<tr>
<td align="center"><a href="https://t.me/paul_docker"><img src="https://avatars1.githubusercontent.com/u/2404785?v=4?s=100" width="100px;" alt=""/><br /><sub><b>田浩</b></sub></a><br /><a href="#content-llitfkitfk" title="Content">🖋</a></td>
<td align="center"><a href="https://twitter.com/StPitsios"><img src="https://avatars1.githubusercontent.com/u/6773603?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Stamatis Pitsios</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=pitsios-s" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/qza"><img src="https://avatars3.githubusercontent.com/u/233149?v=4?s=100" width="100px;" alt=""/><br /><sub><b>qza</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=qza" title="Code">💻</a></td>
<td align="center"><a href="http://tschis.github.io"><img src="https://avatars1.githubusercontent.com/u/20662669?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Rodolfo Forte</b></sub></a><br /><a href="#content-Tschis" title="Content">🖋</a></td>
<td align="center"><a href="https://github.com/ankurkaushal"><img src="https://avatars2.githubusercontent.com/u/2236616?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Ankur Kaushal</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ankurkaushal" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/ankurkaushal"><img src="https://avatars2.githubusercontent.com/u/2236616?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Ankur Kaushal</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ankurkaushal" title="Code">💻</a></td>
<td align="center"><a href="https://www.linkedin.com/in/ovidijus-okinskas/"><img src="https://avatars0.githubusercontent.com/u/20372387?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Ovidijus Okinskas</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=okinskas" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/robertt240"><img src="https://avatars1.githubusercontent.com/u/9137432?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Robert Kasperczyk</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=robertt240" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/trautonen"><img src="https://avatars3.githubusercontent.com/u/1641063?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Tapio Rautonen</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=trautonen" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="http://vk.com/yuri.orlov"><img src="https://avatars0.githubusercontent.com/u/1595733?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Yuri Orlov</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=yorlov" title="Code">💻</a></td>
<td align="center"><a href="https://www.linkedin.com/in/varunu28/"><img src="https://avatars0.githubusercontent.com/u/7676016?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Varun Upadhyay</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=varunu28" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/PalAditya"><img src="https://avatars2.githubusercontent.com/u/25523604?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Aditya Pal</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=PalAditya" title="Code">💻</a></td>
@ -215,41 +236,50 @@ This project is licensed under the terms of the MIT license.
<td align="center"><a href="https://github.com/d4gg4d"><img src="https://avatars2.githubusercontent.com/u/99457?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Sami Airaksinen</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=d4gg4d" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/vertti"><img src="https://avatars0.githubusercontent.com/u/557751?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Janne Sinivirta</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=vertti" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/Bobo1239"><img src="https://avatars1.githubusercontent.com/u/2302947?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Boris-Chengbiao Zhou</b></sub></a><br /><a href="#content-Bobo1239" title="Content">🖋</a></td>
</tr>
<tr>
<td align="center"><a href="https://jahhein.github.io"><img src="https://avatars2.githubusercontent.com/u/10779515?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Jacob Hein</b></sub></a><br /><a href="#content-Jahhein" title="Content">🖋</a></td>
<td align="center"><a href="https://github.com/iamrichardjones"><img src="https://avatars3.githubusercontent.com/u/14842151?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Richard Jones</b></sub></a><br /><a href="#content-iamrichardjones" title="Content">🖋</a></td>
<td align="center"><a href="https://rachelcarmena.github.io"><img src="https://avatars0.githubusercontent.com/u/22792183?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Rachel M. Carmena</b></sub></a><br /><a href="#content-rachelcarmena" title="Content">🖋</a></td>
<td align="center"><a href="https://zd-zero.github.io"><img src="https://avatars0.githubusercontent.com/u/21978370?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Zaerald Denze Lungos</b></sub></a><br /><a href="#content-zd-zero" title="Content">🖋</a></td>
</tr>
<tr>
<td align="center"><a href="https://zd-zero.github.io"><img src="https://avatars0.githubusercontent.com/u/21978370?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Zaerald Denze Lungos</b></sub></a><br /><a href="#content-zd-zero" title="Content">🖋</a></td>
<td align="center"><a href="https://webpro.nl"><img src="https://avatars1.githubusercontent.com/u/456426?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Lars Kappert</b></sub></a><br /><a href="#content-webpro" title="Content">🖋</a></td>
<td align="center"><a href="https://xiaod.info"><img src="https://avatars2.githubusercontent.com/u/21277644?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Mike Liu</b></sub></a><br /><a href="#translation-xiaod-dev" title="Translation">🌍</a></td>
<td align="center"><a href="https://github.com/charlesfinley"><img src="https://avatars1.githubusercontent.com/u/6307904?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Matt Dolan</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=charlesfinley" title="Code">💻</a> <a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3Acharlesfinley" title="Reviewed Pull Requests">👀</a></td>
<td align="center"><a href="https://github.com/MananS77"><img src="https://avatars3.githubusercontent.com/u/21033516?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Manan</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3AMananS77" title="Reviewed Pull Requests">👀</a></td>
<td align="center"><a href="https://github.com/nishant"><img src="https://avatars2.githubusercontent.com/u/15331971?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Nishant Arora</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=nishant" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/raja-peeyush-kumar-singh"><img src="https://avatars0.githubusercontent.com/u/5496024?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Peeyush</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=raja-peeyush-kumar-singh" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/nishant"><img src="https://avatars2.githubusercontent.com/u/15331971?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Nishant Arora</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=nishant" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/raja-peeyush-kumar-singh"><img src="https://avatars0.githubusercontent.com/u/5496024?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Peeyush</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=raja-peeyush-kumar-singh" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/ravening"><img src="https://avatars1.githubusercontent.com/u/10645273?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Rakesh</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ravening" title="Code">💻</a> <a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3Aravening" title="Reviewed Pull Requests">👀</a></td>
<td align="center"><a href="https://github.com/vINCENT8888801"><img src="https://avatars0.githubusercontent.com/u/8037883?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Wei Seng</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=vINCENT8888801" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://www.linkedin.com/in/ashish-trivedi-218379135/"><img src="https://avatars3.githubusercontent.com/u/23194128?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Ashish Trivedi</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ashishtrivedi16" title="Code">💻</a></td>
<td align="center"><a href="https://rayyounghong.com"><img src="https://avatars1.githubusercontent.com/u/41055099?v=4?s=100" width="100px;" alt=""/><br /><sub><b>洪月阳</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=RayYH" title="Code">💻</a></td>
<td align="center"><a href="https://xdvrx1.github.io/"><img src="https://avatars0.githubusercontent.com/u/47092464?v=4?s=100" width="100px;" alt=""/><br /><sub><b>xdvrx1</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3Axdvrx1" title="Reviewed Pull Requests">👀</a> <a href="#ideas-xdvrx1" title="Ideas, Planning, & Feedback">🤔</a></td>
<td align="center"><a href="https://github.com/nahteb"><img src="https://avatars3.githubusercontent.com/u/13121570?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Bethan Palmer</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=nahteb" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/ToxicDreamz"><img src="https://avatars0.githubusercontent.com/u/45225562?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Toxic Dreamz</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ToxicDreamz" title="Code">💻</a></td>
<td align="center"><a href="http://subho.xyz"><img src="https://avatars0.githubusercontent.com/u/13291222?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Subhrodip Mohanta</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ohbus" title="Code">💻</a> <a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3Aohbus" title="Reviewed Pull Requests">👀</a> <a href="#maintenance-ohbus" title="Maintenance">🚧</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/nahteb"><img src="https://avatars3.githubusercontent.com/u/13121570?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Bethan Palmer</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=nahteb" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/ToxicDreamz"><img src="https://avatars0.githubusercontent.com/u/45225562?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Toxic Dreamz</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ToxicDreamz" title="Code">💻</a></td>
<td align="center"><a href="http://www.edycutjong.com"><img src="https://avatars1.githubusercontent.com/u/1098102?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Edy Cu Tjong</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=edycutjong" title="Documentation">📖</a></td>
<td align="center"><a href="https://github.com/mkrzywanski"><img src="https://avatars0.githubusercontent.com/u/15279585?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Michał Krzywański</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=mkrzywanski" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://www.stefan-birkner.de"><img src="https://avatars1.githubusercontent.com/u/711349?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Stefan Birkner</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=stefanbirkner" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/fedorskvorcov"><img src="https://avatars3.githubusercontent.com/u/43882212?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Fedor Skvorcov</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=fedorskvorcov" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/samilAyoub"><img src="https://avatars0.githubusercontent.com/u/61546990?v=4?s=100" width="100px;" alt=""/><br /><sub><b>samilAyoub</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=samilAyoub" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/vdlald"><img src="https://avatars0.githubusercontent.com/u/29997701?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Vladislav Golubinov</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=vdlald" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/swarajsaaj"><img src="https://avatars2.githubusercontent.com/u/6285049?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Swaraj</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=swarajsaaj" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/swarajsaaj"><img src="https://avatars2.githubusercontent.com/u/6285049?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Swaraj</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=swarajsaaj" title="Code">💻</a></td>
<td align="center"><a href="http://christophflick.de"><img src="https://avatars0.githubusercontent.com/u/4465376?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Christoph Flick</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ChFlick" title="Documentation">📖</a></td>
<td align="center"><a href="https://github.com/Ascenio"><img src="https://avatars1.githubusercontent.com/u/7662016?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Ascênio</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3AAscenio" title="Reviewed Pull Requests">👀</a></td>
<td align="center"><a href="https://www.linkedin.com/in/domenico-sibilio/"><img src="https://avatars2.githubusercontent.com/u/24280982?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Domenico Sibilio</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=dsibilio" title="Documentation">📖</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/akashchandwani"><img src="https://avatars2.githubusercontent.com/u/3483277?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Akash Chandwani</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3Aakashchandwani" title="Reviewed Pull Requests">👀</a></td>
<td align="center"><a href="http://www.linkedin.com/in/manannikov"><img src="https://avatars2.githubusercontent.com/u/7019769?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Pavlo Manannikov</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=manannikov" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/eimanip"><img src="https://avatars0.githubusercontent.com/u/20307301?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Eiman</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=eimanip" title="Code">💻</a></td>
@ -260,77 +290,43 @@ This project is licensed under the terms of the MIT license.
<td align="center"><a href="https://github.com/gkulkarni2020"><img src="https://avatars3.githubusercontent.com/u/5161548?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Girish Kulkarni</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=gkulkarni2020" title="Documentation">📖</a></td>
<td align="center"><a href="https://github.com/omk13"><img src="https://avatars0.githubusercontent.com/u/59054172?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Omar Karazoun</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=omk13" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/jeff303"><img src="https://avatars0.githubusercontent.com/u/3521562?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Jeff Evans</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=jeff303" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://viveksb007.github.io"><img src="https://avatars1.githubusercontent.com/u/12713808?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Vivek Singh</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=viveksb007" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/siavashsoleymani"><img src="https://avatars2.githubusercontent.com/u/18074419?v=4?s=100" width="100px;" alt=""/><br /><sub><b>siavash</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=siavashsoleymani" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/ruchpeanuts"><img src="https://avatars0.githubusercontent.com/u/29301900?v=4?s=100" width="100px;" alt=""/><br /><sub><b>ruchpeanuts</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ruchpeanuts" title="Documentation">📖</a></td>
<td align="center"><a href="https://github.com/warp125"><img src="https://avatars1.githubusercontent.com/u/48073115?v=4?s=100" width="100px;" alt=""/><br /><sub><b>warp125</b></sub></a><br /><a href="#translation-warp125" title="Translation">🌍</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/warp125"><img src="https://avatars1.githubusercontent.com/u/48073115?v=4?s=100" width="100px;" alt=""/><br /><sub><b>warp125</b></sub></a><br /><a href="#translation-warp125" title="Translation">🌍</a></td>
<td align="center"><a href="http://libkhadir.fr"><img src="https://avatars1.githubusercontent.com/u/45130488?v=4?s=100" width="100px;" alt=""/><br /><sub><b>KHADIR Tayeb</b></sub></a><br /><a href="#translation-tkhadir" title="Translation">🌍</a></td>
<td align="center"><a href="https://github.com/ignite1771"><img src="https://avatars2.githubusercontent.com/u/59446563?v=4?s=100" width="100px;" alt=""/><br /><sub><b>ignite1771</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ignite1771" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/demirhalil"><img src="https://avatars1.githubusercontent.com/u/22895118?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Halil Demir</b></sub></a><br /><a href="#translation-demirhalil" title="Translation">🌍</a></td>
<td align="center"><a href="https://github.com/rohit10000"><img src="https://avatars.githubusercontent.com/u/20845565?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Rohit Singh</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=rohit10000" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/byoungju94"><img src="https://avatars.githubusercontent.com/u/42516378?v=4?s=100" width="100px;" alt=""/><br /><sub><b>byoungju94</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=byoungju94" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/moustafafarhat"><img src="https://avatars.githubusercontent.com/u/38836727?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Moustafa Farhat</b></sub></a><br /><a href="#translation-moustafafarhat" title="Translation">🌍</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/byoungju94"><img src="https://avatars.githubusercontent.com/u/42516378?v=4?s=100" width="100px;" alt=""/><br /><sub><b>byoungju94</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=byoungju94" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/moustafafarhat"><img src="https://avatars.githubusercontent.com/u/38836727?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Moustafa Farhat</b></sub></a><br /><a href="#translation-moustafafarhat" title="Translation">🌍</a></td>
<td align="center"><a href="https://github.com/richardmr36"><img src="https://avatars.githubusercontent.com/u/19147333?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Martel Richard</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=richardmr36" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/va1m"><img src="https://avatars.githubusercontent.com/u/17025445?v=4?s=100" width="100px;" alt=""/><br /><sub><b>va1m</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=va1m" title="Code">💻</a></td>
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<tr>
<td align="center"><a href="https://github.com/noamgrinch"><img src="https://avatars.githubusercontent.com/u/31648669?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Noam Greenshtain</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=noamgrinch" title="Code">💻</a></td>
<td align="center"><a href="https://xuyonghong.cn/"><img src="https://avatars.githubusercontent.com/u/14086462?v=4?s=100" width="100px;" alt=""/><br /><sub><b>yonghong Xu</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=qfxl" title="Documentation">📖</a></td>
<td align="center"><a href="https://www.linkedin.com/in/jinisha-vora"><img src="https://avatars.githubusercontent.com/u/40777762?v=4?s=100" width="100px;" alt=""/><br /><sub><b>jinishavora</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3Ajinishavora" title="Reviewed Pull Requests">👀</a> <a href="https://github.com/iluwatar/java-design-patterns/commits?author=jinishavora" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/eas5"><img src="https://avatars.githubusercontent.com/u/50836521?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Elvys Soares</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=eas5" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/zWeBrain"><img src="https://avatars.githubusercontent.com/u/46642512?v=4?s=100" width="100px;" alt=""/><br /><sub><b>zWeBrain</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=zWeBrain" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/zWeBrain"><img src="https://avatars.githubusercontent.com/u/46642512?v=4?s=100" width="100px;" alt=""/><br /><sub><b>zWeBrain</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=zWeBrain" title="Code">💻</a></td>
<td align="center"><a href="https://al-assad.github.io/notion/"><img src="https://avatars.githubusercontent.com/u/22493821?v=4?s=100" width="100px;" alt=""/><br /><sub><b>余林颖</b></sub></a><br /><a href="#translation-Al-assad" title="Translation">🌍</a></td>
<td align="center"><a href="https://github.com/STudio26"><img src="https://avatars.githubusercontent.com/u/6988911?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Alain</b></sub></a><br /><a href="#translation-STudio26" title="Translation">🌍</a></td>
<td align="center"><a href="https://github.com/DEV-VRUPER"><img src="https://avatars.githubusercontent.com/u/30525467?v=4?s=100" width="100px;" alt=""/><br /><sub><b>VR</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=DEV-VRUPER" title="Documentation">📖</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/JackieNim"><img src="https://avatars.githubusercontent.com/u/4138836?v=4?s=100" width="100px;" alt=""/><br /><sub><b>JackieNim</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=JackieNim" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/EdisonE3"><img src="https://avatars.githubusercontent.com/u/52118917?v=4?s=100" width="100px;" alt=""/><br /><sub><b>EdisonE3</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=EdisonE3" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/tao-sun2"><img src="https://avatars.githubusercontent.com/u/66189688?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Tao</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=tao-sun2" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/JuanManuelAbate"><img src="https://avatars.githubusercontent.com/u/16357060?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Juan Manuel Abate</b></sub></a><br /><a href="#translation-JuanManuelAbate" title="Translation">🌍</a></td>
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<tr>
<td align="center"><a href="https://github.com/Xenilo137"><img src="https://avatars.githubusercontent.com/u/24865069?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Xenilo137</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Xenilo137" title="Code">💻</a></td>
<td align="center"><a href="https://www.linkedin.com/in/souzasamuel/"><img src="https://avatars.githubusercontent.com/u/17254162?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Samuel Souza</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=samuelpsouza" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/marlo2222"><img src="https://avatars.githubusercontent.com/u/40809563?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Marlo Henrique</b></sub></a><br /><a href="#translation-marlo2222" title="Translation">🌍</a></td>
<td align="center"><a href="https://github.com/AndriyPyzh"><img src="https://avatars.githubusercontent.com/u/57706635?v=4?s=100" width="100px;" alt=""/><br /><sub><b>AndriyPyzh</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=AndriyPyzh" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/karthikbhat13"><img src="https://avatars.githubusercontent.com/u/22431014?v=4?s=100" width="100px;" alt=""/><br /><sub><b>karthikbhat13</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=karthikbhat13" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/mortezaadi"><img src="https://avatars.githubusercontent.com/u/1329687?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Morteza Adigozalpour</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=mortezaadi" title="Code">💻</a></td>
<td align="center"><a href="https://stackoverflow.com/users/308565/nagaraj-tantri"><img src="https://avatars.githubusercontent.com/u/3784194?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Nagaraj Tantri</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=tan31989" title="Code">💻</a></td>
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<tr>
<td align="center"><a href="http://scuccimarri.it"><img src="https://avatars.githubusercontent.com/u/7107651?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Francesco Scuccimarri</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=frascu" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/Conhan93"><img src="https://avatars.githubusercontent.com/u/71334757?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Conny Hansson</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Conhan93" title="Documentation">📖</a></td>
<td align="center"><a href="http://muklasr.medium.com"><img src="https://avatars.githubusercontent.com/u/43443753?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Muklas Rahmanto</b></sub></a><br /><a href="#translation-muklasr" title="Translation">🌍</a></td>
<td align="center"><a href="https://github.com/VxDxK"><img src="https://avatars.githubusercontent.com/u/38704817?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Vadim</b></sub></a><br /><a href="#translation-VxDxK" title="Translation">🌍</a></td>
<td align="center"><a href="https://github.com/sims-keshri"><img src="https://avatars.githubusercontent.com/u/62168475?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Simran Keshri</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=sims-keshri" title="Code">💻</a></td>
<td align="center"><a href="https://programacionymas.com"><img src="https://avatars.githubusercontent.com/u/3101238?v=4?s=100" width="100px;" alt=""/><br /><sub><b>JCarlos</b></sub></a><br /><a href="#translation-JCarlosR" title="Translation">🌍</a></td>
<td align="center"><a href="https://www.mrmoshkel.ir"><img src="https://avatars.githubusercontent.com/u/60359433?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Ali Ghasemi</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Dev-AliGhasemi" title="Code">💻</a></td>
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<tr>
<td align="center"><a href="http://carlfx.wordpress.com"><img src="https://avatars.githubusercontent.com/u/1594624?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Carl Dea</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=carldea" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/Mozartuss"><img src="https://avatars.githubusercontent.com/u/32893711?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Mozartus</b></sub></a><br /><a href="#translation-Mozartuss" title="Translation">🌍</a></td>
<td align="center"><a href="https://github.com/ManviGoel26"><img src="https://avatars.githubusercontent.com/u/55682355?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Manvi Goel</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ManviGoel26" title="Documentation">📖</a></td>
<td align="center"><a href="https://github.com/blueberry404"><img src="https://avatars.githubusercontent.com/u/39243539?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Anum Amin</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=blueberry404" title="Documentation">📖</a></td>
<td align="center"><a href="https://uh-zz.github.io/blog/"><img src="https://avatars.githubusercontent.com/u/47747828?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Reo Uehara</b></sub></a><br /><a href="#translation-uh-zz" title="Translation">🌍</a></td>
<td align="center"><a href="https://github.com/Fiordy"><img src="https://avatars.githubusercontent.com/u/53420573?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Fiordy</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Fiordy" title="Documentation">📖</a></td>
<td align="center"><a href="https://github.com/harshalkh"><img src="https://avatars.githubusercontent.com/u/37841724?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Harshal</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=harshalkh" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://www.linkedin.com/in/abhinav-vashisth-06613b208/"><img src="https://avatars.githubusercontent.com/u/89785800?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Abhinav Vashisth</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=vashisthabhinav" title="Documentation">📖</a></td>
<td align="center"><a href="http://no website"><img src="https://avatars.githubusercontent.com/u/47126749?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Kevin</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3AKevinyl3" title="Reviewed Pull Requests">👀</a> <a href="https://github.com/iluwatar/java-design-patterns/commits?author=Kevinyl3" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/Shrirang97"><img src="https://avatars.githubusercontent.com/u/28738668?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Shrirang</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3AShrirang97" title="Reviewed Pull Requests">👀</a> <a href="https://github.com/iluwatar/java-design-patterns/commits?author=Shrirang97" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/interactwithankush"><img src="https://avatars.githubusercontent.com/u/18613127?v=4?s=100" width="100px;" alt=""/><br /><sub><b>interactwithankush</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=interactwithankush" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/yuhangbin"><img src="https://avatars.githubusercontent.com/u/17566866?v=4?s=100" width="100px;" alt=""/><br /><sub><b>CharlieYu</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=yuhangbin" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/Leisterbecker"><img src="https://avatars.githubusercontent.com/u/20650323?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Leisterbecker</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Leisterbecker" title="Code">💻</a></td>
<td align="center"><a href="http://rosaecrucis.cn"><img src="https://avatars.githubusercontent.com/u/35420129?v=4?s=100" width="100px;" alt=""/><br /><sub><b>DragonDreamer</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=castleKing1997" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/ShivanshCharak"><img src="https://avatars.githubusercontent.com/u/96943825?v=4?s=100" width="100px;" alt=""/><br /><sub><b>ShivanshCharak</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ShivanshCharak" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/HattoriHenzo"><img src="https://avatars.githubusercontent.com/u/5141285?v=4?s=100" width="100px;" alt=""/><br /><sub><b>HattoriHenzo</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=HattoriHenzo" title="Code">💻</a></td>
</tr>
</table>
<!-- markdownlint-restore -->

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@ -23,40 +23,42 @@
THE SOFTWARE.
-->
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in parent pom and specifying the class having main method -->
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@ -87,36 +87,24 @@ public interface KingdomFactory {
}
public class ElfKingdomFactory implements KingdomFactory {
@Override
public Castle createCastle() {
return new ElfCastle();
}
@Override
public King createKing() {
return new ElfKing();
}
@Override
public Army createArmy() {
return new ElfArmy();
}
}
public class OrcKingdomFactory implements KingdomFactory {
@Override
public Castle createCastle() {
return new OrcCastle();
}
@Override
public King createKing() {
return new OrcKing();
}
@Override
public Army createArmy() {
return new OrcArmy();
}
@ -208,13 +196,13 @@ Example use cases
* Unit test case writing becomes much easier
* UI tools for different OS
## Consequences
## Consequences:
* Dependency injection in java hides the service class dependencies that can lead to runtime errors that would have been caught at compile time.
* While the pattern is great when creating predefined objects, adding the new ones might be challenging.
* The code becomes more complicated than it should be since a lot of new interfaces and classes are introduced along with the pattern.
## Tutorials
## Tutorial
* [Abstract Factory Pattern Tutorial](https://www.journaldev.com/1418/abstract-factory-design-pattern-in-java)

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@ -1,4 +1,4 @@
<?xml version="1.0" encoding="UTF-8"?>
<?xml version="1.0"?>
<!--
The MIT License
@ -23,40 +23,43 @@
THE SOFTWARE.
-->
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in parent pom and specifying the class having main method -->
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
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@ -11,7 +11,7 @@ tags:
## Intent
The active object design pattern decouples method execution from method invocation for objects that each reside in their thread of control. The goal is to introduce concurrency, by using asynchronous method invocation, and a scheduler for handling requests.
The active object design pattern decouples method execution from method invocation for objects that each reside in their thread of control. The goal is to introduce concurrency, by using asynchronous method invocation and a scheduler for handling requests.
## Explanation
@ -70,7 +70,7 @@ public abstract class ActiveCreature{
requests.put(new Runnable() {
@Override
public void run() {
logger.info("{} has started to roam the wastelands.",name());
logger.info("{} has started to roam and the wastelands.",name());
}
}
);
@ -82,7 +82,7 @@ public abstract class ActiveCreature{
}
```
We can see that any class that will extend the ActiveCreature class will have its own thread of control to invoke and execute methods.
We can see that any class that will extend the ActiveCreature class will have its own thread of control to execute and invocate methods.
For example, the Orc class:
@ -96,7 +96,7 @@ public class Orc extends ActiveCreature {
}
```
Now, we can create multiple creatures such as Orcs, tell them to eat and roam, and they will execute it on their own thread of control:
Now, we can create multiple creatures such as Orcs, tell them to eat and roam and they will execute it on their own thread of control:
```java
public static void main(String[] args) {
@ -123,8 +123,4 @@ Now, we can create multiple creatures such as Orcs, tell them to eat and roam, a
## Class diagram
![alt text](./etc/active-object.urm.png "Active Object class diagram")
## Tutorials
* [Android and Java Concurrency: The Active Object Pattern](https://www.youtube.com/watch?v=Cd8t2u5Qmvc)
![alt text](./etc/active-object.urm.PNG "Active Object class diagram")

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@ -1,4 +1,4 @@
<?xml version="1.0" encoding="UTF-8"?>
<?xml version="1.0"?>
<!--
The MIT License
@ -23,40 +23,43 @@
THE SOFTWARE.
-->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.iluwatar</groupId>
<artifactId>java-design-patterns</artifactId>
<version>1.26.0-SNAPSHOT</version>
</parent>
<artifactId>active-object</artifactId>
<dependencies>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
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<project
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
xmlns="http://maven.apache.org/POM/4.0.0"
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<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
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<build>
<plugins>
<!-- Maven assembly plugin is invoked with default setting which we have
in parent pom and specifying the class having main method -->
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
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<groupId>org.apache.maven.plugins</groupId>
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@ -82,7 +82,7 @@ public abstract class ActiveCreature {
}
/**
* Roam the wastelands.
* Roam in the wastelands.
* @throws InterruptedException due to firing a new Runnable.
*/
public void roam() throws InterruptedException {

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@ -138,10 +138,6 @@ This pattern can be used:
* When the visited class hierarchy will be frequently extended with new derivatives of the Element class.
* When the recompilation, relinking, retesting or redistribution of the derivatives of Element is very expensive.
## Tutorial
* [Acyclic Visitor Pattern Example](https://codecrafter.blogspot.com/2012/12/the-acyclic-visitor-pattern.html)
## Consequences
The good:

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@ -1,4 +1,3 @@
<?xml version="1.0" encoding="UTF-8"?>
<!--
The MIT License
@ -23,47 +22,53 @@
THE SOFTWARE.
-->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.iluwatar</groupId>
<artifactId>java-design-patterns</artifactId>
<version>1.26.0-SNAPSHOT</version>
</parent>
<artifactId>acyclic-visitor</artifactId>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
</properties>
<dependencies>
<!-- https://mvnrepository.com/artifact/org.assertj/assertj-core -->
<dependency>
<groupId>org.assertj</groupId>
<artifactId>assertj-core</artifactId>
<version>3.9.1</version>
<scope>test</scope>
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<!-- https://mvnrepository.com/artifact/uk.org.lidalia/slf4j-test -->
<dependency>
<groupId>uk.org.lidalia</groupId>
<artifactId>slf4j-test</artifactId>
<version>1.2.0</version>
<scope>test</scope>
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<version>1.10.19</version>
<scope>test</scope>
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<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
</properties>
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<!-- https://mvnrepository.com/artifact/org.assertj/assertj-core -->
<dependency>
<groupId>org.assertj</groupId>
<artifactId>assertj-core</artifactId>
<version>3.9.1</version>
<scope>test</scope>
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<!-- https://mvnrepository.com/artifact/uk.org.lidalia/slf4j-test -->
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<groupId>uk.org.lidalia</groupId>
<artifactId>slf4j-test</artifactId>
<version>1.2.0</version>
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<version>1.10.19</version>
<scope>test</scope>
</dependency>
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in parent pom and specifying the class having main method -->

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@ -29,7 +29,7 @@ import lombok.extern.slf4j.Slf4j;
* Hayes class implements its accept method.
*/
@Slf4j
public class Hayes implements Modem {
public class Hayes extends Modem {
/**
* Accepts all visitors but honors only HayesVisitor.

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@ -24,9 +24,8 @@
package com.iluwatar.acyclicvisitor;
/**
* //Modem abstract class.
* converted to an interface
* Modem abstract class.
*/
public interface Modem {
void accept(ModemVisitor modemVisitor);
public abstract class Modem {
public abstract void accept(ModemVisitor modemVisitor);
}

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@ -29,7 +29,7 @@ import lombok.extern.slf4j.Slf4j;
* Zoom class implements its accept method.
*/
@Slf4j
public class Zoom implements Modem {
public class Zoom extends Modem {
/**
* Accepts all visitors but honors only ZoomVisitor.

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@ -18,10 +18,10 @@ couldn't otherwise because of incompatible interfaces.
## Explanation
Real-world example
Real world example
> Consider that you have some pictures on your memory card and you need to transfer them to your computer. To transfer them, you need some kind of adapter that is compatible with your computer ports so that you can attach a memory card to your computer. In this case card reader is an adapter.
> Another example would be the famous power adapter; a three-legged plug can't be connected to a two-pronged outlet, it needs to use a power adapter that makes it compatible with the two-pronged outlets.
> Consider that you have some pictures in your memory card and you need to transfer them to your computer. In order to transfer them you need some kind of adapter that is compatible with your computer ports so that you can attach memory card to your computer. In this case card reader is an adapter.
> Another example would be the famous power adapter; a three legged plug can't be connected to a two pronged outlet, it needs to use a power adapter that makes it compatible with the two pronged outlet.
> Yet another example would be a translator translating words spoken by one person to another
In plain words
@ -36,7 +36,7 @@ Wikipedia says
Consider a captain that can only use rowing boats and cannot sail at all.
First, we have interfaces `RowingBoat` and `FishingBoat`
First we have interfaces `RowingBoat` and `FishingBoat`
```java
public interface RowingBoat {
@ -68,7 +68,7 @@ public class Captain {
}
```
Now let's say the pirates are coming and our captain needs to escape but there is only a fishing boat available. We need to create an adapter that allows the captain to operate the fishing boat with his rowing boat skills.
Now let's say the pirates are coming and our captain needs to escape but there is only fishing boat available. We need to create an adapter that allows the captain to operate the fishing boat with his rowing boat skills.
```java
@Slf4j
@ -100,31 +100,25 @@ captain.row();
## Applicability
Use the Adapter pattern when
* You want to use an existing class, and its interface does not match the one you need
* You want to create a reusable class that cooperates with unrelated or unforeseen classes, that is, classes that don't necessarily have compatible interfaces
* You need to use several existing subclasses, but it's impractical to adapt their interface by subclassing everyone. An object adapter can adapt the interface of its parent class.
* Most of the applications using third-party libraries use adapters as a middle layer between the application and the 3rd party library to decouple the application from the library. If another library has to be used only an adapter for the new library is required without having to change the application code.
* you want to use an existing class, and its interface does not match the one you need
* you want to create a reusable class that cooperates with unrelated or unforeseen classes, that is, classes that don't necessarily have compatible interfaces
* you need to use several existing subclasses, but it's impractical to adapt their interface by subclassing every one. An object adapter can adapt the interface of its parent class.
* most of the applications using third party libraries use adapters as a middle layer between the application and the 3rd party library to decouple the application from the library. If another library has to be used only an adapter for the new library is required without having to change the application code.
## Tutorials
* [Dzone](https://dzone.com/articles/adapter-design-pattern-in-java)
* [Refactoring Guru](https://refactoring.guru/design-patterns/adapter/java/example)
* [Baeldung](https://www.baeldung.com/java-adapter-pattern)
## Consequences
## Consequences:
Class and object adapters have different trade-offs. A class adapter
* Adapts Adaptee to Target by committing to a concrete Adaptee class. As a consequence, a class adapter wont work when we want to adapt a class and all its subclasses.
* Lets Adapter override some of Adaptees behavior since Adapter is a subclass of Adaptee.
* Introduces only one object, and no additional pointer indirection is needed to get to the adaptee.
* adapts Adaptee to Target by committing to a concrete Adaptee class. As a consequence, a class adapter wont work when we want to adapt a class and all its subclasses.
* lets Adapter override some of Adaptees behavior, since Adapter is a subclass of Adaptee.
* introduces only one object, and no additional pointer indirection is needed to get to the adaptee.
An object adapter
* Lets a single Adapter work with many Adaptees—that is, the Adaptee itself and all of its subclasses (if any). The Adapter can also add functionality to all Adaptees at once.
* Makes it harder to override Adaptee behavior. It will require subclassing Adaptee and making the Adapter refer to the subclass rather than the Adaptee itself.
* lets a single Adapter work with many Adaptees—that is, the Adaptee itself and all of its subclasses (if any). The Adapter can also add functionality to all Adaptees at once.
* makes it harder to override Adaptee behavior. It will require subclassing Adaptee and making Adapter refer to the subclass rather than the Adaptee itself.
## Real-world examples
## Real world examples
* [java.util.Arrays#asList()](http://docs.oracle.com/javase/8/docs/api/java/util/Arrays.html#asList%28T...%29)
* [java.util.Collections#list()](https://docs.oracle.com/javase/8/docs/api/java/util/Collections.html#list-java.util.Enumeration-)

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@ -1,4 +1,4 @@
<?xml version="1.0" encoding="UTF-8"?>
<?xml version="1.0"?>
<!--
The MIT License
@ -23,45 +23,48 @@
THE SOFTWARE.
-->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.iluwatar</groupId>
<artifactId>java-design-patterns</artifactId>
<version>1.26.0-SNAPSHOT</version>
</parent>
<artifactId>adapter</artifactId>
<dependencies>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.mockito</groupId>
<artifactId>mockito-core</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<!-- Maven assembly plugin is invoked with default setting which we have
<project
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.iluwatar</groupId>
<artifactId>java-design-patterns</artifactId>
<version>1.25.0-SNAPSHOT</version>
</parent>
<artifactId>adapter</artifactId>
<dependencies>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.mockito</groupId>
<artifactId>mockito-core</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<!-- Maven assembly plugin is invoked with default setting which we have
in parent pom and specifying the class having main method -->
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<configuration>
<archive>
<manifest>
<mainClass>com.iluwatar.adapter.App</mainClass>
</manifest>
</archive>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<configuration>
<archive>
<manifest>
<mainClass>com.iluwatar.adapter.App</mainClass>
</manifest>
</archive>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>

View File

@ -33,7 +33,7 @@ import static org.mockito.Mockito.spy;
import static org.mockito.Mockito.verify;
/**
* Tests for the adapter pattern.
* Test class
*/
class AdapterPatternTest {

View File

@ -33,7 +33,9 @@ import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
class AppTest {
/**
* Check whether the execution of the main method in {@link App}
* Issue: Add at least one assertion to this test case.
*
* Solution: Inserted assertion to check whether the execution of the main method in {@link App}
* throws an exception.
*/

View File

@ -23,65 +23,68 @@
THE SOFTWARE.
-->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>aggregator-microservices</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.26.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>aggregator-service</artifactId>
<packaging>jar</packaging>
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.mockito</groupId>
<artifactId>mockito-core</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
</execution>
</executions>
</plugin>
<!-- Maven assembly plugin is invoked with default setting which we have
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>aggregator-microservices</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.25.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>aggregator-service</artifactId>
<packaging>jar</packaging>
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.mockito</groupId>
<artifactId>mockito-core</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
</execution>
</executions>
</plugin>
<!-- Maven assembly plugin is invoked with default setting which we have
in parent pom and specifying the class having main method -->
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<configuration>
<archive>
<manifest>
<mainClass>com.iluwatar.aggregator.microservices.App</mainClass>
</manifest>
</archive>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<configuration>
<archive>
<manifest>
<mainClass>com.iluwatar.aggregator.microservices.App</mainClass>
</manifest>
</archive>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>

View File

@ -48,7 +48,7 @@ class AggregatorTest {
@BeforeEach
public void setup() {
MockitoAnnotations.openMocks(this);
MockitoAnnotations.initMocks(this);
}
/**

View File

@ -23,58 +23,63 @@
THE SOFTWARE.
-->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>aggregator-microservices</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.26.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>information-microservice</artifactId>
<packaging>jar</packaging>
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<configuration>
<archive>
<manifest>
<mainClass>com.iluwatar.information.microservices.InformationApplication</mainClass>
</manifest>
</archive>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>aggregator-microservices</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.25.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>information-microservice</artifactId>
<packaging>jar</packaging>
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<configuration>
<archive>
<manifest>
<mainClass>com.iluwatar.information.microservices.InformationApplication</mainClass>
</manifest>
</archive>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>

View File

@ -23,58 +23,62 @@
THE SOFTWARE.
-->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>aggregator-microservices</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.26.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>inventory-microservice</artifactId>
<packaging>jar</packaging>
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<configuration>
<archive>
<manifest>
<mainClass>com.iluwatar.inventory.microservices.InventoryApplication</mainClass>
</manifest>
</archive>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>aggregator-microservices</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.25.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>inventory-microservice</artifactId>
<packaging>jar</packaging>
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<configuration>
<archive>
<manifest>
<mainClass>com.iluwatar.inventory.microservices.InventoryApplication</mainClass>
</manifest>
</archive>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>

View File

@ -23,18 +23,20 @@
THE SOFTWARE.
-->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>java-design-patterns</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.26.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>aggregator-microservices</artifactId>
<packaging>pom</packaging>
<modules>
<module>information-microservice</module>
<module>aggregator-service</module>
<module>inventory-microservice</module>
</modules>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>java-design-patterns</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.25.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>aggregator-microservices</artifactId>
<packaging>pom</packaging>
<modules>
<module>information-microservice</module>
<module>aggregator-service</module>
<module>inventory-microservice</module>
</modules>
</project>

View File

@ -23,38 +23,40 @@
THE SOFTWARE.
-->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>java-design-patterns</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.26.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>ambassador</artifactId>
<dependencies>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<configuration>
<archive>
<manifest>
<mainClass>com.iluwatar.ambassador.App</mainClass>
</manifest>
</archive>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>java-design-patterns</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.25.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>ambassador</artifactId>
<dependencies>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<configuration>
<archive>
<manifest>
<mainClass>com.iluwatar.ambassador.App</mainClass>
</manifest>
</archive>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>

View File

@ -23,11 +23,13 @@
THE SOFTWARE.
-->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>api-gateway</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.26.0-SNAPSHOT</version>
<version>1.25.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>api-gateway-service</artifactId>
@ -52,6 +54,7 @@
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>

View File

@ -48,7 +48,7 @@ class ApiGatewayTest {
@BeforeEach
public void setup() {
MockitoAnnotations.openMocks(this);
MockitoAnnotations.initMocks(this);
}
/**

View File

@ -23,11 +23,13 @@
THE SOFTWARE.
-->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>api-gateway</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.26.0-SNAPSHOT</version>
<version>1.25.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>image-microservice</artifactId>
@ -47,6 +49,7 @@
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>

View File

@ -23,11 +23,13 @@
THE SOFTWARE.
-->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>java-design-patterns</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.26.0-SNAPSHOT</version>
<version>1.25.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>api-gateway</artifactId>

View File

@ -23,15 +23,19 @@
THE SOFTWARE.
-->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>api-gateway</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.26.0-SNAPSHOT</version>
<version>1.25.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>price-microservice</artifactId>
<packaging>jar</packaging>
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
@ -47,6 +51,7 @@
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>

View File

@ -23,13 +23,16 @@
THE SOFTWARE.
-->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>java-design-patterns</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.26.0-SNAPSHOT</version>
<version>1.25.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>arrange-act-assert</artifactId>
<dependencies>
<dependency>
@ -38,4 +41,4 @@
<scope>test</scope>
</dependency>
</dependencies>
</project>
</project>

View File

@ -1,4 +1,4 @@
<?xml version="1.0" encoding="UTF-8"?>
<?xml version="1.0"?>
<!--
The MIT License
@ -23,43 +23,46 @@
THE SOFTWARE.
-->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.iluwatar</groupId>
<artifactId>java-design-patterns</artifactId>
<version>1.26.0-SNAPSHOT</version>
</parent>
<artifactId>async-method-invocation</artifactId>
<dependencies>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.mockito</groupId>
<artifactId>mockito-core</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<configuration>
<archive>
<manifest>
<mainClass>com.iluwatar.async.method.invocation.App</mainClass>
</manifest>
</archive>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
<project
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.iluwatar</groupId>
<artifactId>java-design-patterns</artifactId>
<version>1.25.0-SNAPSHOT</version>
</parent>
<artifactId>async-method-invocation</artifactId>
<dependencies>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.mockito</groupId>
<artifactId>mockito-core</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<configuration>
<archive>
<manifest>
<mainClass>com.iluwatar.async.method.invocation.App</mainClass>
</manifest>
</archive>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>

View File

@ -59,12 +59,9 @@ import lombok.extern.slf4j.Slf4j;
@Slf4j
public class App {
private static final String ROCKET_LAUNCH_LOG_PATTERN = "Space rocket <%s> launched successfully";
/**
* Program entry point.
*/
public static void main(String[] args) throws Exception {
// construct a new executor that will run async tasks
var executor = new ThreadAsyncExecutor();
@ -90,9 +87,9 @@ public class App {
asyncResult5.await();
// log the results of the tasks, callbacks log immediately when complete
log(String.format(ROCKET_LAUNCH_LOG_PATTERN, result1));
log(String.format(ROCKET_LAUNCH_LOG_PATTERN, result2));
log(String.format(ROCKET_LAUNCH_LOG_PATTERN, result3));
log("Space rocket <" + result1 + "> launch complete");
log("Space rocket <" + result2 + "> launch complete");
log("Space rocket <" + result3 + "> launch complete");
}
/**
@ -105,7 +102,7 @@ public class App {
private static <T> Callable<T> lazyval(T value, long delayMillis) {
return () -> {
Thread.sleep(delayMillis);
log(String.format(ROCKET_LAUNCH_LOG_PATTERN, value));
log("Space rocket <" + value + "> launched successfully");
return value;
};
}

View File

@ -68,7 +68,7 @@ class ThreadAsyncExecutorTest {
@BeforeEach
void setUp() {
MockitoAnnotations.openMocks(this);
MockitoAnnotations.initMocks(this);
}
/**

View File

@ -23,38 +23,41 @@
THE SOFTWARE.
-->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>java-design-patterns</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.26.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>balking</artifactId>
<dependencies>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<configuration>
<archive>
<manifest>
<mainClass>com.iluwatar.balking.App</mainClass>
</manifest>
</archive>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>java-design-patterns</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.25.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>balking</artifactId>
<dependencies>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<configuration>
<archive>
<manifest>
<mainClass>com.iluwatar.balking.App</mainClass>
</manifest>
</archive>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>

View File

@ -19,7 +19,7 @@ Decouple an abstraction from its implementation so that the two can vary indepen
## Explanation
Real-world example
Real world example
> Consider you have a weapon with different enchantments, and you are supposed to allow mixing
> different weapons with different enchantments. What would you do? Create multiple copies of each
@ -161,36 +161,27 @@ public class SoulEatingEnchantment implements Enchantment {
Here are both hierarchies in action:
```java
LOGGER.info("The knight receives an enchanted sword.");
var enchantedSword = new Sword(new SoulEatingEnchantment());
enchantedSword.wield();
enchantedSword.swing();
enchantedSword.unwield();
// The sword is wielded.
// The item spreads bloodlust.
// The sword is swinged.
// The item eats the soul of enemies.
// The sword is unwielded.
// Bloodlust slowly disappears.
LOGGER.info("The valkyrie receives an enchanted hammer.");
var hammer = new Hammer(new FlyingEnchantment());
hammer.wield();
hammer.swing();
hammer.unwield();
```
Here's the console output.
```
The knight receives an enchanted sword.
The sword is wielded.
The item spreads bloodlust.
The sword is swung.
The item eats the soul of enemies.
The sword is unwielded.
Bloodlust slowly disappears.
The valkyrie receives an enchanted hammer.
The hammer is wielded.
The item begins to glow faintly.
The hammer is swung.
The item flies and strikes the enemies finally returning to owner's hand.
The hammer is unwielded.
The item's glow fades.
// The hammer is wielded.
// The item begins to glow faintly.
// The hammer is swinged.
// The item flies and strikes the enemies finally returning to owner's hand.
// The hammer is unwielded.
// The item's glow fades.
```
## Class diagram

View File

@ -1,4 +1,4 @@
<?xml version="1.0" encoding="UTF-8"?>
<?xml version="1.0"?>
<!--
The MIT License
@ -23,27 +23,30 @@
THE SOFTWARE.
-->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.iluwatar</groupId>
<artifactId>java-design-patterns</artifactId>
<version>1.26.0-SNAPSHOT</version>
</parent>
<artifactId>bridge</artifactId>
<dependencies>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.mockito</groupId>
<artifactId>mockito-core</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<project
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.iluwatar</groupId>
<artifactId>java-design-patterns</artifactId>
<version>1.25.0-SNAPSHOT</version>
</parent>
<artifactId>bridge</artifactId>
<dependencies>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.mockito</groupId>
<artifactId>mockito-core</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>

View File

@ -16,11 +16,11 @@ process can create different representations.
## Explanation
Real-world example
Real world example
> Imagine a character generator for a role-playing game. The easiest option is to let the computer
> create the character for you. If you want to manually select the character details like
> profession, gender, hair color, etc. the character generation becomes a step-by-step process that
> profession, gender, hair color etc. the character generation becomes a step-by-step process that
> completes when all the selections are ready.
In plain words
@ -49,7 +49,7 @@ anti-pattern.
**Programmatic Example**
The sane alternative is to use the Builder pattern. First of all, we have our hero that we want to
The sane alternative is to use the Builder pattern. First of all we have our hero that we want to
create:
```java
@ -134,13 +134,7 @@ Use the Builder pattern when
* The algorithm for creating a complex object should be independent of the parts that make up the object and how they're assembled
* The construction process must allow different representations for the object that's constructed
## Tutorials
* [Refactoring Guru](https://refactoring.guru/design-patterns/builder)
* [Oracle Blog](https://blogs.oracle.com/javamagazine/post/exploring-joshua-blochs-builder-design-pattern-in-java)
* [Journal Dev](https://www.journaldev.com/1425/builder-design-pattern-in-java)
## Known uses
## Real world examples
* [java.lang.StringBuilder](http://docs.oracle.com/javase/8/docs/api/java/lang/StringBuilder.html)
* [java.nio.ByteBuffer](http://docs.oracle.com/javase/8/docs/api/java/nio/ByteBuffer.html#put-byte-) as well as similar buffers such as FloatBuffer, IntBuffer and so on.

View File

@ -1,4 +1,4 @@
<?xml version="1.0" encoding="UTF-8"?>
<?xml version="1.0"?>
<!--
The MIT License
@ -23,22 +23,25 @@
THE SOFTWARE.
-->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.iluwatar</groupId>
<artifactId>java-design-patterns</artifactId>
<version>1.26.0-SNAPSHOT</version>
</parent>
<artifactId>builder</artifactId>
<dependencies>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<project
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.iluwatar</groupId>
<artifactId>java-design-patterns</artifactId>
<version>1.25.0-SNAPSHOT</version>
</parent>
<artifactId>builder</artifactId>
<dependencies>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>

View File

@ -1,4 +1,4 @@
<?xml version="1.0" encoding="UTF-8"?>
<?xml version="1.0"?>
<!--
The MIT License
@ -23,43 +23,46 @@
THE SOFTWARE.
-->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.iluwatar</groupId>
<artifactId>java-design-patterns</artifactId>
<version>1.26.0-SNAPSHOT</version>
</parent>
<artifactId>business-delegate</artifactId>
<dependencies>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.mockito</groupId>
<artifactId>mockito-core</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<configuration>
<archive>
<manifest>
<mainClass>com.iluwatar.business.delegate.App</mainClass>
</manifest>
</archive>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
<project
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.iluwatar</groupId>
<artifactId>java-design-patterns</artifactId>
<version>1.25.0-SNAPSHOT</version>
</parent>
<artifactId>business-delegate</artifactId>
<dependencies>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.mockito</groupId>
<artifactId>mockito-core</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<configuration>
<archive>
<manifest>
<mainClass>com.iluwatar.business.delegate.App</mainClass>
</manifest>
</archive>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>

View File

@ -23,38 +23,43 @@
THE SOFTWARE.
-->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>java-design-patterns</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.26.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>bytecode</artifactId>
<dependencies>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<configuration>
<archive>
<manifest>
<mainClass>com.iluwatar.bytecode.App</mainClass>
</manifest>
</archive>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>java-design-patterns</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.25.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>bytecode</artifactId>
<dependencies>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<configuration>
<archive>
<manifest>
<mainClass>com.iluwatar.bytecode.App</mainClass>
</manifest>
</archive>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>

View File

@ -42,14 +42,6 @@ import lombok.extern.slf4j.Slf4j;
@Slf4j
public class App {
private static final String LITERAL_0 = "LITERAL 0";
private static final String HEALTH_PATTERN = "%s_HEALTH";
private static final String GET_AGILITY = "GET_AGILITY";
private static final String GET_WISDOM = "GET_WISDOM";
private static final String ADD = "ADD";
private static final String LITERAL_2 = "LITERAL 2";
private static final String DIVIDE = "DIVIDE";
/**
* Main app method.
*
@ -61,17 +53,17 @@ public class App {
new Wizard(45, 7, 11, 0, 0),
new Wizard(36, 18, 8, 0, 0));
vm.execute(InstructionConverterUtil.convertToByteCode(LITERAL_0));
vm.execute(InstructionConverterUtil.convertToByteCode(LITERAL_0));
vm.execute(InstructionConverterUtil.convertToByteCode(String.format(HEALTH_PATTERN, "GET")));
vm.execute(InstructionConverterUtil.convertToByteCode(LITERAL_0));
vm.execute(InstructionConverterUtil.convertToByteCode(GET_AGILITY));
vm.execute(InstructionConverterUtil.convertToByteCode(LITERAL_0));
vm.execute(InstructionConverterUtil.convertToByteCode(GET_WISDOM));
vm.execute(InstructionConverterUtil.convertToByteCode(ADD));
vm.execute(InstructionConverterUtil.convertToByteCode(LITERAL_2));
vm.execute(InstructionConverterUtil.convertToByteCode(DIVIDE));
vm.execute(InstructionConverterUtil.convertToByteCode(ADD));
vm.execute(InstructionConverterUtil.convertToByteCode(String.format(HEALTH_PATTERN, "SET")));
vm.execute(InstructionConverterUtil.convertToByteCode("LITERAL 0"));
vm.execute(InstructionConverterUtil.convertToByteCode("LITERAL 0"));
vm.execute(InstructionConverterUtil.convertToByteCode("GET_HEALTH"));
vm.execute(InstructionConverterUtil.convertToByteCode("LITERAL 0"));
vm.execute(InstructionConverterUtil.convertToByteCode("GET_AGILITY"));
vm.execute(InstructionConverterUtil.convertToByteCode("LITERAL 0"));
vm.execute(InstructionConverterUtil.convertToByteCode("GET_WISDOM"));
vm.execute(InstructionConverterUtil.convertToByteCode("ADD"));
vm.execute(InstructionConverterUtil.convertToByteCode("LITERAL 2"));
vm.execute(InstructionConverterUtil.convertToByteCode("DIVIDE"));
vm.execute(InstructionConverterUtil.convertToByteCode("ADD"));
vm.execute(InstructionConverterUtil.convertToByteCode("SET_HEALTH"));
}
}

View File

@ -43,29 +43,39 @@ Wikipedia says:
**Programmatic Example**
Let's first look at the data layer of our application. The interesting classes are `UserAccount`
which is a simple Java object containing the user account details, and `DbManager` interface which handles
reading and writing of these objects to/from database.
which is a simple Java object containing the user account details, and `DbManager` which handles
reading and writing of these objects to/from MongoDB database.
```java
@Data
@Setter
@Getter
@AllArgsConstructor
@ToString
@EqualsAndHashCode
public class UserAccount {
private String userId;
private String userName;
private String additionalInfo;
}
public interface DbManager {
@Slf4j
public final class DbManager {
void connect();
void disconnect();
UserAccount readFromDb(String userId);
UserAccount writeToDb(UserAccount userAccount);
UserAccount updateDb(UserAccount userAccount);
UserAccount upsertDb(UserAccount userAccount);
private static MongoClient mongoClient;
private static MongoDatabase db;
private DbManager() { /*...*/ }
public static void createVirtualDb() { /*...*/ }
public static void connect() throws ParseException { /*...*/ }
public static UserAccount readFromDb(String userId) { /*...*/ }
public static void writeToDb(UserAccount userAccount) { /*...*/ }
public static void updateDb(UserAccount userAccount) { /*...*/ }
public static void upsertDb(UserAccount userAccount) { /*...*/ }
}
```
@ -161,43 +171,30 @@ strategies.
@Slf4j
public class CacheStore {
private static final int CAPACITY = 3;
private static LruCache cache;
private final DbManager dbManager;
/* ... details omitted ... */
public UserAccount readThrough(final String userId) {
public static UserAccount readThrough(String userId) {
if (cache.contains(userId)) {
LOGGER.info("# Found in Cache!");
LOGGER.info("# Cache Hit!");
return cache.get(userId);
}
LOGGER.info("# Not found in cache! Go to DB!!");
UserAccount userAccount = dbManager.readFromDb(userId);
LOGGER.info("# Cache Miss!");
UserAccount userAccount = DbManager.readFromDb(userId);
cache.set(userId, userAccount);
return userAccount;
}
public void writeThrough(final UserAccount userAccount) {
public static void writeThrough(UserAccount userAccount) {
if (cache.contains(userAccount.getUserId())) {
dbManager.updateDb(userAccount);
DbManager.updateDb(userAccount);
} else {
dbManager.writeToDb(userAccount);
DbManager.writeToDb(userAccount);
}
cache.set(userAccount.getUserId(), userAccount);
}
public void writeAround(final UserAccount userAccount) {
if (cache.contains(userAccount.getUserId())) {
dbManager.updateDb(userAccount);
// Cache data has been updated -- remove older
cache.invalidate(userAccount.getUserId());
// version from cache.
} else {
dbManager.writeToDb(userAccount);
}
}
public static void clearCache() {
if (cache != null) {
cache.clear();
@ -228,39 +225,34 @@ class.
public final class AppManager {
private static CachingPolicy cachingPolicy;
private final DbManager dbManager;
private final CacheStore cacheStore;
private AppManager() {
}
public void initDb() { /* ... */ }
public static void initDb(boolean useMongoDb) { /* ... */ }
public static void initCachingPolicy(CachingPolicy policy) { /* ... */ }
public static void initCacheCapacity(int capacity) { /* ... */ }
public UserAccount find(final String userId) {
LOGGER.info("Trying to find {} in cache", userId);
if (cachingPolicy == CachingPolicy.THROUGH
|| cachingPolicy == CachingPolicy.AROUND) {
return cacheStore.readThrough(userId);
public static UserAccount find(String userId) {
if (cachingPolicy == CachingPolicy.THROUGH || cachingPolicy == CachingPolicy.AROUND) {
return CacheStore.readThrough(userId);
} else if (cachingPolicy == CachingPolicy.BEHIND) {
return cacheStore.readThroughWithWriteBackPolicy(userId);
return CacheStore.readThroughWithWriteBackPolicy(userId);
} else if (cachingPolicy == CachingPolicy.ASIDE) {
return findAside(userId);
}
return null;
}
public void save(final UserAccount userAccount) {
LOGGER.info("Save record!");
public static void save(UserAccount userAccount) {
if (cachingPolicy == CachingPolicy.THROUGH) {
cacheStore.writeThrough(userAccount);
CacheStore.writeThrough(userAccount);
} else if (cachingPolicy == CachingPolicy.AROUND) {
cacheStore.writeAround(userAccount);
CacheStore.writeAround(userAccount);
} else if (cachingPolicy == CachingPolicy.BEHIND) {
cacheStore.writeBehind(userAccount);
CacheStore.writeBehind(userAccount);
} else if (cachingPolicy == CachingPolicy.ASIDE) {
saveAside(userAccount);
}
@ -280,35 +272,24 @@ Here is what we do in the main class of the application.
@Slf4j
public class App {
public static void main(final String[] args) {
boolean isDbMongo = isDbMongo(args);
if(isDbMongo){
LOGGER.info("Using the Mongo database engine to run the application.");
} else {
LOGGER.info("Using the 'in Memory' database to run the application.");
}
App app = new App(isDbMongo);
public static void main(String[] args) {
AppManager.initDb(false);
AppManager.initCacheCapacity(3);
var app = new App();
app.useReadAndWriteThroughStrategy();
String splitLine = "==============================================";
LOGGER.info(splitLine);
app.useReadThroughAndWriteAroundStrategy();
LOGGER.info(splitLine);
app.useReadThroughAndWriteBehindStrategy();
LOGGER.info(splitLine);
app.useCacheAsideStategy();
LOGGER.info(splitLine);
}
public void useReadAndWriteThroughStrategy() {
LOGGER.info("# CachingPolicy.THROUGH");
appManager.initCachingPolicy(CachingPolicy.THROUGH);
AppManager.initCachingPolicy(CachingPolicy.THROUGH);
var userAccount1 = new UserAccount("001", "John", "He is a boy.");
appManager.save(userAccount1);
LOGGER.info(appManager.printCacheContent());
appManager.find("001");
appManager.find("001");
AppManager.save(userAccount1);
LOGGER.info(AppManager.printCacheContent());
AppManager.find("001");
AppManager.find("001");
}
public void useReadThroughAndWriteAroundStrategy() { /* ... */ }
@ -319,6 +300,16 @@ public class App {
}
```
Finally, here is some of the console output from the program.
```
12:32:53.845 [main] INFO com.iluwatar.caching.App - # CachingPolicy.THROUGH
12:32:53.900 [main] INFO com.iluwatar.caching.App -
--CACHE CONTENT--
UserAccount(userId=001, userName=John, additionalInfo=He is a boy.)
----
```
## Class diagram
![alt text](./etc/caching.png "Caching")

View File

@ -1,11 +0,0 @@
version: '3.7'
services:
mongodb_container:
image: mongo:latest
environment:
MONGO_INITDB_ROOT_USERNAME: root
MONGO_INITDB_ROOT_PASSWORD: rootpassword
ports:
- 27017:27017
volumes:
- ./mongo-data/:/data/db

BIN
caching/etc/caching.png Normal file

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@ -1,4 +1,4 @@
<?xml version="1.0" encoding="UTF-8"?>
<?xml version="1.0"?>
<!--
The MIT License
@ -23,12 +23,13 @@
THE SOFTWARE.
-->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.iluwatar</groupId>
<artifactId>java-design-patterns</artifactId>
<version>1.26.0-SNAPSHOT</version>
<version>1.25.0-SNAPSHOT</version>
</parent>
<artifactId>caching</artifactId>
<dependencies>
@ -38,14 +39,19 @@
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.mockito</groupId>
<artifactId>mockito-all</artifactId>
<version>1.10.19</version>
<scope>test</scope>
<groupId>org.mongodb</groupId>
<artifactId>mongodb-driver</artifactId>
<version>3.12.1</version>
</dependency>
<dependency>
<groupId>org.mongodb</groupId>
<artifactId>mongo-java-driver</artifactId>
<artifactId>mongodb-driver-core</artifactId>
<version>3.0.4</version>
</dependency>
<dependency>
<groupId>org.mongodb</groupId>
<artifactId>bson</artifactId>
<version>3.0.4</version>
</dependency>
</dependencies>
<!--

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@ -1,62 +1,58 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.caching;
import com.iluwatar.caching.database.DbManager;
import com.iluwatar.caching.database.DbManagerFactory;
import lombok.extern.slf4j.Slf4j;
/**
* The Caching pattern describes how to avoid expensive re-acquisition of
* resources by not releasing the resources immediately after their use.
* The resources retain their identity, are kept in some fast-access storage,
* and are re-used to avoid having to acquire them again. There are four main
* caching strategies/techniques in this pattern; each with their own pros and
* cons. They are <code>write-through</code> which writes data to the cache and
* DB in a single transaction, <code>write-around</code> which writes data
* immediately into the DB instead of the cache, <code>write-behind</code>
* which writes data into the cache initially whilst the data is only
* written into the DB when the cache is full, and <code>cache-aside</code>
* which pushes the responsibility of keeping the data synchronized in both
* data sources to the application itself. The <code>read-through</code>
* strategy is also included in the mentioned four strategies --
* returns data from the cache to the caller <b>if</b> it exists <b>else</b>
* queries from DB and stores it into the cache for future use. These strategies
* determine when the data in the cache should be written back to the backing
* store (i.e. Database) and help keep both data sources
* synchronized/up-to-date. This pattern can improve performance and also helps
* to maintainconsistency between data held in the cache and the data in
* the underlying data store.
* The Caching pattern describes how to avoid expensive re-acquisition of resources by not releasing
* the resources immediately after their use. The resources retain their identity, are kept in some
* fast-access storage, and are re-used to avoid having to acquire them again. There are four main
* caching strategies/techniques in this pattern; each with their own pros and cons. They are;
* <code>write-through</code> which writes data to the cache and DB in a single transaction,
* <code>write-around</code> which writes data immediately into the DB instead of the cache,
* <code>write-behind</code> which writes data into the cache initially whilst the data is only
* written into the DB when the cache is full, and <code>cache-aside</code> which pushes the
* responsibility of keeping the data synchronized in both data sources to the application itself.
* The <code>read-through</code> strategy is also included in the mentioned four strategies --
* returns data from the cache to the caller <b>if</b> it exists <b>else</b> queries from DB and
* stores it into the cache for future use. These strategies determine when the data in the cache
* should be written back to the backing store (i.e. Database) and help keep both data sources
* synchronized/up-to-date. This pattern can improve performance and also helps to maintain
* consistency between data held in the cache and the data in the underlying data store.
*
* <p>In this example, the user account ({@link UserAccount}) entity is used
* as the underlying application data. The cache itself is implemented as an
* internal (Java) data structure. It adopts a Least-Recently-Used (LRU)
* strategy for evicting data from itself when its full. The four
* strategies are individually tested. The testing of the cache is restricted
* towards saving and querying of user accounts from the
* underlying data store( {@link DbManager}). The main class ( {@link App}
* is not aware of the underlying mechanics of the application
* (i.e. save and query) and whether the data is coming from the cache or the
* DB (i.e. separation of concern). The AppManager ({@link AppManager}) handles
* the transaction of data to-and-from the underlying data store (depending on
* the preferred caching policy/strategy).
* <p>In this example, the user account ({@link UserAccount}) entity is used as the underlying
* application data. The cache itself is implemented as an internal (Java) data structure. It adopts
* a Least-Recently-Used (LRU) strategy for evicting data from itself when its full. The four
* strategies are individually tested. The testing of the cache is restricted towards saving and
* querying of user accounts from the underlying data store ( {@link DbManager}). The main class (
* {@link App} is not aware of the underlying mechanics of the application (i.e. save and query) and
* whether the data is coming from the cache or the DB (i.e. separation of concern). The AppManager
* ({@link AppManager}) handles the transaction of data to-and-from the underlying data store
* (depending on the preferred caching policy/strategy).
* <p>
* <i>{@literal App --> AppManager --> CacheStore/LRUCache/CachingPolicy -->
* DBManager} </i>
* </p>
*
* <p>
* There are 2 ways to launch the application.
* - to use "in Memory" database.
* - to use the MongoDb as a database
*
* To run the application with "in Memory" database, just launch it without parameters
* Example: 'java -jar app.jar'
*
* To run the application with MongoDb you need to be installed the MongoDb
* in your system, or to launch it in the docker container.
* You may launch docker container from the root of current module with command:
* 'docker-compose up'
* Then you can start the application with parameter --mongo
* Example: 'java -jar app.jar --mongo'
* <i>{@literal App --> AppManager --> CacheStore/LRUCache/CachingPolicy --> DBManager} </i>
* </p>
*
* @see CacheStore
@ -65,67 +61,23 @@ import lombok.extern.slf4j.Slf4j;
*/
@Slf4j
public class App {
/**
* Constant parameter name to use mongoDB.
*/
private static final String USE_MONGO_DB = "--mongo";
/**
* Application manager.
*/
private final AppManager appManager;
/**
* Constructor of current App.
*
* @param isMongo boolean
*/
public App(final boolean isMongo) {
DbManager dbManager = DbManagerFactory.initDb(isMongo);
appManager = new AppManager(dbManager);
appManager.initDb();
}
/**
* Program entry point.
*
* @param args command line args
*/
public static void main(final String[] args) {
// VirtualDB (instead of MongoDB) was used in running the JUnit tests
public static void main(String[] args) {
AppManager.initDb(false); // VirtualDB (instead of MongoDB) was used in running the JUnit tests
// and the App class to avoid Maven compilation errors. Set flag to
// true to run the tests with MongoDB (provided that MongoDB is
// installed and socket connection is open).
boolean isDbMongo = isDbMongo(args);
if (isDbMongo) {
LOGGER.info("Using the Mongo database engine to run the application.");
} else {
LOGGER.info("Using the 'in Memory' database to run the application.");
}
App app = new App(isDbMongo);
AppManager.initCacheCapacity(3);
var app = new App();
app.useReadAndWriteThroughStrategy();
String splitLine = "==============================================";
LOGGER.info(splitLine);
app.useReadThroughAndWriteAroundStrategy();
LOGGER.info(splitLine);
app.useReadThroughAndWriteBehindStrategy();
LOGGER.info(splitLine);
app.useCacheAsideStategy();
LOGGER.info(splitLine);
}
/**
* Check the input parameters. if
*
* @param args input params
* @return true if there is "--mongo" parameter in arguments
*/
private static boolean isDbMongo(final String[] args) {
for (String arg : args) {
if (arg.equals(USE_MONGO_DB)) {
return true;
}
}
return false;
}
/**
@ -133,14 +85,14 @@ public class App {
*/
public void useReadAndWriteThroughStrategy() {
LOGGER.info("# CachingPolicy.THROUGH");
appManager.initCachingPolicy(CachingPolicy.THROUGH);
AppManager.initCachingPolicy(CachingPolicy.THROUGH);
var userAccount1 = new UserAccount("001", "John", "He is a boy.");
appManager.save(userAccount1);
LOGGER.info(appManager.printCacheContent());
appManager.find("001");
appManager.find("001");
AppManager.save(userAccount1);
LOGGER.info(AppManager.printCacheContent());
AppManager.find("001");
AppManager.find("001");
}
/**
@ -148,21 +100,21 @@ public class App {
*/
public void useReadThroughAndWriteAroundStrategy() {
LOGGER.info("# CachingPolicy.AROUND");
appManager.initCachingPolicy(CachingPolicy.AROUND);
AppManager.initCachingPolicy(CachingPolicy.AROUND);
var userAccount2 = new UserAccount("002", "Jane", "She is a girl.");
appManager.save(userAccount2);
LOGGER.info(appManager.printCacheContent());
appManager.find("002");
LOGGER.info(appManager.printCacheContent());
userAccount2 = appManager.find("002");
AppManager.save(userAccount2);
LOGGER.info(AppManager.printCacheContent());
AppManager.find("002");
LOGGER.info(AppManager.printCacheContent());
userAccount2 = AppManager.find("002");
userAccount2.setUserName("Jane G.");
appManager.save(userAccount2);
LOGGER.info(appManager.printCacheContent());
appManager.find("002");
LOGGER.info(appManager.printCacheContent());
appManager.find("002");
AppManager.save(userAccount2);
LOGGER.info(AppManager.printCacheContent());
AppManager.find("002");
LOGGER.info(AppManager.printCacheContent());
AppManager.find("002");
}
/**
@ -170,31 +122,23 @@ public class App {
*/
public void useReadThroughAndWriteBehindStrategy() {
LOGGER.info("# CachingPolicy.BEHIND");
appManager.initCachingPolicy(CachingPolicy.BEHIND);
AppManager.initCachingPolicy(CachingPolicy.BEHIND);
var userAccount3 = new UserAccount("003",
"Adam",
"He likes food.");
var userAccount4 = new UserAccount("004",
"Rita",
"She hates cats.");
var userAccount5 = new UserAccount("005",
"Isaac",
"He is allergic to mustard.");
var userAccount3 = new UserAccount("003", "Adam", "He likes food.");
var userAccount4 = new UserAccount("004", "Rita", "She hates cats.");
var userAccount5 = new UserAccount("005", "Isaac", "He is allergic to mustard.");
appManager.save(userAccount3);
appManager.save(userAccount4);
appManager.save(userAccount5);
LOGGER.info(appManager.printCacheContent());
appManager.find("003");
LOGGER.info(appManager.printCacheContent());
UserAccount userAccount6 = new UserAccount("006",
"Yasha",
"She is an only child.");
appManager.save(userAccount6);
LOGGER.info(appManager.printCacheContent());
appManager.find("004");
LOGGER.info(appManager.printCacheContent());
AppManager.save(userAccount3);
AppManager.save(userAccount4);
AppManager.save(userAccount5);
LOGGER.info(AppManager.printCacheContent());
AppManager.find("003");
LOGGER.info(AppManager.printCacheContent());
UserAccount userAccount6 = new UserAccount("006", "Yasha", "She is an only child.");
AppManager.save(userAccount6);
LOGGER.info(AppManager.printCacheContent());
AppManager.find("004");
LOGGER.info(AppManager.printCacheContent());
}
/**
@ -202,26 +146,20 @@ public class App {
*/
public void useCacheAsideStategy() {
LOGGER.info("# CachingPolicy.ASIDE");
appManager.initCachingPolicy(CachingPolicy.ASIDE);
LOGGER.info(appManager.printCacheContent());
AppManager.initCachingPolicy(CachingPolicy.ASIDE);
LOGGER.info(AppManager.printCacheContent());
var userAccount3 = new UserAccount("003",
"Adam",
"He likes food.");
var userAccount4 = new UserAccount("004",
"Rita",
"She hates cats.");
var userAccount5 = new UserAccount("005",
"Isaac",
"He is allergic to mustard.");
appManager.save(userAccount3);
appManager.save(userAccount4);
appManager.save(userAccount5);
var userAccount3 = new UserAccount("003", "Adam", "He likes food.");
var userAccount4 = new UserAccount("004", "Rita", "She hates cats.");
var userAccount5 = new UserAccount("005", "Isaac", "He is allergic to mustard.");
AppManager.save(userAccount3);
AppManager.save(userAccount4);
AppManager.save(userAccount5);
LOGGER.info(appManager.printCacheContent());
appManager.find("003");
LOGGER.info(appManager.printCacheContent());
appManager.find("004");
LOGGER.info(appManager.printCacheContent());
LOGGER.info(AppManager.printCacheContent());
AppManager.find("003");
LOGGER.info(AppManager.printCacheContent());
AppManager.find("004");
LOGGER.info(AppManager.printCacheContent());
}
}

View File

@ -23,80 +23,65 @@
package com.iluwatar.caching;
import com.iluwatar.caching.database.DbManager;
import java.text.ParseException;
import java.util.Optional;
import lombok.extern.slf4j.Slf4j;
/**
* AppManager helps to bridge the gap in communication between the main class
* and the application's back-end. DB connection is initialized through this
* class. The chosen caching strategy/policy is also initialized here.
* Before the cache can be used, the size of the cache has to be set.
* Depending on the chosen caching policy, AppManager will call the
* appropriate function in the CacheStore class.
* AppManager helps to bridge the gap in communication between the main class and the application's
* back-end. DB connection is initialized through this class. The chosen caching strategy/policy is
* also initialized here. Before the cache can be used, the size of the cache has to be set.
* Depending on the chosen caching policy, AppManager will call the appropriate function in the
* CacheStore class.
*/
@Slf4j
public class AppManager {
/**
* Caching Policy.
*/
private CachingPolicy cachingPolicy;
/**
* Database Manager.
*/
private final DbManager dbManager;
/**
* Cache Store.
*/
private final CacheStore cacheStore;
public final class AppManager {
/**
* Constructor.
*
* @param newDbManager database manager
*/
public AppManager(final DbManager newDbManager) {
this.dbManager = newDbManager;
this.cacheStore = new CacheStore(newDbManager);
private static CachingPolicy cachingPolicy;
private AppManager() {
}
/**
* Developer/Tester is able to choose whether the application should use
* MongoDB as its underlying data storage or a simple Java data structure
* to (temporarily) store the data/objects during runtime.
* Developer/Tester is able to choose whether the application should use MongoDB as its underlying
* data storage or a simple Java data structure to (temporarily) store the data/objects during
* runtime.
*/
public void initDb() {
dbManager.connect();
public static void initDb(boolean useMongoDb) {
if (useMongoDb) {
try {
DbManager.connect();
} catch (ParseException e) {
LOGGER.error("Error connecting to MongoDB", e);
}
} else {
DbManager.createVirtualDb();
}
}
/**
* Initialize caching policy.
*
* @param policy is a {@link CachingPolicy}
*/
public void initCachingPolicy(final CachingPolicy policy) {
public static void initCachingPolicy(CachingPolicy policy) {
cachingPolicy = policy;
if (cachingPolicy == CachingPolicy.BEHIND) {
Runtime.getRuntime().addShutdownHook(new Thread(cacheStore::flushCache));
Runtime.getRuntime().addShutdownHook(new Thread(CacheStore::flushCache));
}
cacheStore.clearCache();
CacheStore.clearCache();
}
public static void initCacheCapacity(int capacity) {
CacheStore.initCapacity(capacity);
}
/**
* Find user account.
*
* @param userId String
* @return {@link UserAccount}
*/
public UserAccount find(final String userId) {
LOGGER.info("Trying to find {} in cache", userId);
if (cachingPolicy == CachingPolicy.THROUGH
|| cachingPolicy == CachingPolicy.AROUND) {
return cacheStore.readThrough(userId);
public static UserAccount find(String userId) {
if (cachingPolicy == CachingPolicy.THROUGH || cachingPolicy == CachingPolicy.AROUND) {
return CacheStore.readThrough(userId);
} else if (cachingPolicy == CachingPolicy.BEHIND) {
return cacheStore.readThroughWithWriteBackPolicy(userId);
return CacheStore.readThroughWithWriteBackPolicy(userId);
} else if (cachingPolicy == CachingPolicy.ASIDE) {
return findAside(userId);
}
@ -105,55 +90,41 @@ public class AppManager {
/**
* Save user account.
*
* @param userAccount {@link UserAccount}
*/
public void save(final UserAccount userAccount) {
LOGGER.info("Save record!");
public static void save(UserAccount userAccount) {
if (cachingPolicy == CachingPolicy.THROUGH) {
cacheStore.writeThrough(userAccount);
CacheStore.writeThrough(userAccount);
} else if (cachingPolicy == CachingPolicy.AROUND) {
cacheStore.writeAround(userAccount);
CacheStore.writeAround(userAccount);
} else if (cachingPolicy == CachingPolicy.BEHIND) {
cacheStore.writeBehind(userAccount);
CacheStore.writeBehind(userAccount);
} else if (cachingPolicy == CachingPolicy.ASIDE) {
saveAside(userAccount);
}
}
/**
* Returns String.
*
* @return String
*/
public String printCacheContent() {
return cacheStore.print();
public static String printCacheContent() {
return CacheStore.print();
}
/**
* Cache-Aside save user account helper.
*
* @param userAccount {@link UserAccount}
*/
private void saveAside(final UserAccount userAccount) {
dbManager.updateDb(userAccount);
cacheStore.invalidate(userAccount.getUserId());
private static void saveAside(UserAccount userAccount) {
DbManager.updateDb(userAccount);
CacheStore.invalidate(userAccount.getUserId());
}
/**
* Cache-Aside find user account helper.
*
* @param userId String
* @return {@link UserAccount}
*/
private UserAccount findAside(final String userId) {
return Optional.ofNullable(cacheStore.get(userId))
.or(() -> {
Optional<UserAccount> userAccount =
Optional.ofNullable(dbManager.readFromDb(userId));
userAccount.ifPresent(account -> cacheStore.set(userId, account));
return userAccount;
})
.orElse(null);
private static UserAccount findAside(String userId) {
return Optional.ofNullable(CacheStore.get(userId))
.or(() -> {
Optional<UserAccount> userAccount = Optional.ofNullable(DbManager.readFromDb(userId));
userAccount.ifPresent(account -> CacheStore.set(userId, account));
return userAccount;
})
.orElse(null);
}
}

View File

@ -23,11 +23,9 @@
package com.iluwatar.caching;
import com.iluwatar.caching.database.DbManager;
import java.util.List;
import java.util.Optional;
import java.util.stream.Collectors;
import lombok.extern.slf4j.Slf4j;
/**
@ -35,34 +33,16 @@ import lombok.extern.slf4j.Slf4j;
*/
@Slf4j
public class CacheStore {
/**
* Cache capacity.
*/
private static final int CAPACITY = 3;
/**
* Lru cache see {@link LruCache}.
*/
private LruCache cache;
/**
* DbManager.
*/
private final DbManager dbManager;
private static LruCache cache;
/**
* Cache Store.
* @param dataBaseManager {@link DbManager}
*/
public CacheStore(final DbManager dataBaseManager) {
this.dbManager = dataBaseManager;
initCapacity(CAPACITY);
private CacheStore() {
}
/**
* Init cache capacity.
* @param capacity int
*/
public void initCapacity(final int capacity) {
public static void initCapacity(int capacity) {
if (cache == null) {
cache = new LruCache(capacity);
} else {
@ -72,64 +52,57 @@ public class CacheStore {
/**
* Get user account using read-through cache.
* @param userId {@link String}
* @return {@link UserAccount}
*/
public UserAccount readThrough(final String userId) {
public static UserAccount readThrough(String userId) {
if (cache.contains(userId)) {
LOGGER.info("# Found in Cache!");
LOGGER.info("# Cache Hit!");
return cache.get(userId);
}
LOGGER.info("# Not found in cache! Go to DB!!");
UserAccount userAccount = dbManager.readFromDb(userId);
LOGGER.info("# Cache Miss!");
UserAccount userAccount = DbManager.readFromDb(userId);
cache.set(userId, userAccount);
return userAccount;
}
/**
* Get user account using write-through cache.
* @param userAccount {@link UserAccount}
*/
public void writeThrough(final UserAccount userAccount) {
public static void writeThrough(UserAccount userAccount) {
if (cache.contains(userAccount.getUserId())) {
dbManager.updateDb(userAccount);
DbManager.updateDb(userAccount);
} else {
dbManager.writeToDb(userAccount);
DbManager.writeToDb(userAccount);
}
cache.set(userAccount.getUserId(), userAccount);
}
/**
* Get user account using write-around cache.
* @param userAccount {@link UserAccount}
*/
public void writeAround(final UserAccount userAccount) {
public static void writeAround(UserAccount userAccount) {
if (cache.contains(userAccount.getUserId())) {
dbManager.updateDb(userAccount);
// Cache data has been updated -- remove older
cache.invalidate(userAccount.getUserId());
DbManager.updateDb(userAccount);
cache.invalidate(userAccount.getUserId()); // Cache data has been updated -- remove older
// version from cache.
} else {
dbManager.writeToDb(userAccount);
DbManager.writeToDb(userAccount);
}
}
/**
* Get user account using read-through cache with write-back policy.
* @param userId {@link String}
* @return {@link UserAccount}
*/
public UserAccount readThroughWithWriteBackPolicy(final String userId) {
public static UserAccount readThroughWithWriteBackPolicy(String userId) {
if (cache.contains(userId)) {
LOGGER.info("# Found in cache!");
LOGGER.info("# Cache Hit!");
return cache.get(userId);
}
LOGGER.info("# Not found in Cache!");
UserAccount userAccount = dbManager.readFromDb(userId);
LOGGER.info("# Cache Miss!");
UserAccount userAccount = DbManager.readFromDb(userId);
if (cache.isFull()) {
LOGGER.info("# Cache is FULL! Writing LRU data to DB...");
UserAccount toBeWrittenToDb = cache.getLruData();
dbManager.upsertDb(toBeWrittenToDb);
DbManager.upsertDb(toBeWrittenToDb);
}
cache.set(userId, userAccount);
return userAccount;
@ -137,13 +110,12 @@ public class CacheStore {
/**
* Set user account.
* @param userAccount {@link UserAccount}
*/
public void writeBehind(final UserAccount userAccount) {
public static void writeBehind(UserAccount userAccount) {
if (cache.isFull() && !cache.contains(userAccount.getUserId())) {
LOGGER.info("# Cache is FULL! Writing LRU data to DB...");
UserAccount toBeWrittenToDb = cache.getLruData();
dbManager.upsertDb(toBeWrittenToDb);
DbManager.upsertDb(toBeWrittenToDb);
}
cache.set(userAccount.getUserId(), userAccount);
}
@ -151,7 +123,7 @@ public class CacheStore {
/**
* Clears cache.
*/
public void clearCache() {
public static void clearCache() {
if (cache != null) {
cache.clear();
}
@ -160,51 +132,44 @@ public class CacheStore {
/**
* Writes remaining content in the cache into the DB.
*/
public void flushCache() {
public static void flushCache() {
LOGGER.info("# flushCache...");
Optional.ofNullable(cache)
.map(LruCache::getCacheDataInListForm)
.orElse(List.of())
.forEach(dbManager::updateDb);
dbManager.disconnect();
.forEach(DbManager::updateDb);
}
/**
* Print user accounts.
* @return {@link String}
*/
public String print() {
public static String print() {
return Optional.ofNullable(cache)
.map(LruCache::getCacheDataInListForm)
.orElse(List.of())
.stream()
.map(userAccount -> userAccount.toString() + "\n")
.collect(Collectors.joining("", "\n--CACHE CONTENT--\n", "----"));
.collect(Collectors.joining("", "\n--CACHE CONTENT--\n", "----\n"));
}
/**
* Delegate to backing cache store.
* @param userId {@link String}
* @return {@link UserAccount}
*/
public UserAccount get(final String userId) {
public static UserAccount get(String userId) {
return cache.get(userId);
}
/**
* Delegate to backing cache store.
* @param userId {@link String}
* @param userAccount {@link UserAccount}
*/
public void set(final String userId, final UserAccount userAccount) {
public static void set(String userId, UserAccount userAccount) {
cache.set(userId, userAccount);
}
/**
* Delegate to backing cache store.
* @param userId {@link String}
*/
public void invalidate(final String userId) {
public static void invalidate(String userId) {
cache.invalidate(userId);
}
}

View File

@ -32,25 +32,10 @@ import lombok.Getter;
@AllArgsConstructor
@Getter
public enum CachingPolicy {
/**
* Through.
*/
THROUGH("through"),
/**
* AROUND.
*/
AROUND("around"),
/**
* BEHIND.
*/
BEHIND("behind"),
/**
* ASIDE.
*/
ASIDE("aside");
/**
* Policy value.
*/
private final String policy;
}

View File

@ -0,0 +1,171 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.caching;
import com.iluwatar.caching.constants.CachingConstants;
import com.mongodb.MongoClient;
import com.mongodb.client.MongoDatabase;
import com.mongodb.client.model.UpdateOptions;
import java.text.ParseException;
import java.util.HashMap;
import java.util.Map;
import lombok.extern.slf4j.Slf4j;
import org.bson.Document;
/**
* <p>DBManager handles the communication with the underlying data store i.e. Database. It contains
* the implemented methods for querying, inserting, and updating data. MongoDB was used as the
* database for the application.</p>
*
* <p>Developer/Tester is able to choose whether the application should use MongoDB as its
* underlying data storage (connect()) or a simple Java data structure to (temporarily) store the
* data/objects during runtime (createVirtualDB()).</p>
*/
@Slf4j
public final class DbManager {
private static MongoClient mongoClient;
private static MongoDatabase db;
private static boolean useMongoDB;
private static Map<String, UserAccount> virtualDB;
private DbManager() {
}
/**
* Create DB.
*/
public static void createVirtualDb() {
useMongoDB = false;
virtualDB = new HashMap<>();
}
/**
* Connect to DB.
*/
public static void connect() throws ParseException {
useMongoDB = true;
mongoClient = new MongoClient();
db = mongoClient.getDatabase("test");
}
/**
* Read user account from DB.
*/
public static UserAccount readFromDb(String userId) {
if (!useMongoDB) {
if (virtualDB.containsKey(userId)) {
return virtualDB.get(userId);
}
return null;
}
if (db == null) {
try {
connect();
} catch (ParseException e) {
LOGGER.error("Error connecting to MongoDB", e);
}
}
var iterable = db
.getCollection(CachingConstants.USER_ACCOUNT)
.find(new Document(CachingConstants.USER_ID, userId));
if (iterable == null) {
return null;
}
Document doc = iterable.first();
String userName = doc.getString(CachingConstants.USER_NAME);
String appInfo = doc.getString(CachingConstants.ADD_INFO);
return new UserAccount(userId, userName, appInfo);
}
/**
* Write user account to DB.
*/
public static void writeToDb(UserAccount userAccount) {
if (!useMongoDB) {
virtualDB.put(userAccount.getUserId(), userAccount);
return;
}
if (db == null) {
try {
connect();
} catch (ParseException e) {
LOGGER.error("Error connecting to MongoDB", e);
}
}
db.getCollection(CachingConstants.USER_ACCOUNT).insertOne(
new Document(CachingConstants.USER_ID, userAccount.getUserId())
.append(CachingConstants.USER_NAME, userAccount.getUserName())
.append(CachingConstants.ADD_INFO, userAccount.getAdditionalInfo())
);
}
/**
* Update DB.
*/
public static void updateDb(UserAccount userAccount) {
if (!useMongoDB) {
virtualDB.put(userAccount.getUserId(), userAccount);
return;
}
if (db == null) {
try {
connect();
} catch (ParseException e) {
LOGGER.error("Error connecting to MongoDB", e);
}
}
db.getCollection(CachingConstants.USER_ACCOUNT).updateOne(
new Document(CachingConstants.USER_ID, userAccount.getUserId()),
new Document("$set", new Document(CachingConstants.USER_NAME, userAccount.getUserName())
.append(CachingConstants.ADD_INFO, userAccount.getAdditionalInfo())));
}
/**
* Insert data into DB if it does not exist. Else, update it.
*/
public static void upsertDb(UserAccount userAccount) {
if (!useMongoDB) {
virtualDB.put(userAccount.getUserId(), userAccount);
return;
}
if (db == null) {
try {
connect();
} catch (ParseException e) {
LOGGER.error("Error connecting to MongoDB", e);
}
}
db.getCollection(CachingConstants.USER_ACCOUNT).updateOne(
new Document(CachingConstants.USER_ID, userAccount.getUserId()),
new Document("$set",
new Document(CachingConstants.USER_ID, userAccount.getUserId())
.append(CachingConstants.USER_NAME, userAccount.getUserName())
.append(CachingConstants.ADD_INFO, userAccount.getAdditionalInfo())
),
new UpdateOptions().upsert(true)
);
}
}

View File

@ -29,83 +29,41 @@ import java.util.List;
import java.util.Map;
import lombok.extern.slf4j.Slf4j;
/**
* Data structure/implementation of the application's cache. The data structure
* consists of a hash table attached with a doubly linked-list. The linked-list
* helps in capturing and maintaining the LRU data in the cache. When a data is
* queried (from the cache), added (to the cache), or updated, the data is
* moved to the front of the list to depict itself as the most-recently-used
* data. The LRU data is always at the end of the list.
* Data structure/implementation of the application's cache. The data structure consists of a hash
* table attached with a doubly linked-list. The linked-list helps in capturing and maintaining the
* LRU data in the cache. When a data is queried (from the cache), added (to the cache), or updated,
* the data is moved to the front of the list to depict itself as the most-recently-used data. The
* LRU data is always at the end of the list.
*/
@Slf4j
public class LruCache {
/**
* Static class Node.
*/
static class Node {
/**
* user id.
*/
private final String userId;
/**
* User Account.
*/
private UserAccount userAccount;
/**
* previous.
*/
private Node previous;
/**
* next.
*/
private Node next;
/**
* Node definition.
*
* @param id String
* @param account {@link UserAccount}
*/
Node(final String id, final UserAccount account) {
this.userId = id;
this.userAccount = account;
static class Node {
String userId;
UserAccount userAccount;
Node previous;
Node next;
public Node(String userId, UserAccount userAccount) {
this.userId = userId;
this.userAccount = userAccount;
}
}
/**
* Capacity of Cache.
*/
private int capacity;
/**
* Cache {@link HashMap}.
*/
private Map<String, Node> cache = new HashMap<>();
/**
* Head.
*/
private Node head;
/**
* End.
*/
private Node end;
int capacity;
Map<String, Node> cache = new HashMap<>();
Node head;
Node end;
/**
* Constructor.
*
* @param cap Integer.
*/
public LruCache(final int cap) {
this.capacity = cap;
public LruCache(int capacity) {
this.capacity = capacity;
}
/**
* Get user account.
*
* @param userId String
* @return {@link UserAccount}
*/
public UserAccount get(final String userId) {
public UserAccount get(String userId) {
if (cache.containsKey(userId)) {
var node = cache.get(userId);
remove(node);
@ -117,10 +75,8 @@ public class LruCache {
/**
* Remove node from linked list.
*
* @param node {@link Node}
*/
public void remove(final Node node) {
public void remove(Node node) {
if (node.previous != null) {
node.previous.next = node.next;
} else {
@ -135,10 +91,8 @@ public class LruCache {
/**
* Move node to the front of the list.
*
* @param node {@link Node}
*/
public void setHead(final Node node) {
public void setHead(Node node) {
node.next = head;
node.previous = null;
if (head != null) {
@ -152,11 +106,8 @@ public class LruCache {
/**
* Set user account.
*
* @param userAccount {@link UserAccount}
* @param userId {@link String}
*/
public void set(final String userId, final UserAccount userAccount) {
public void set(String userId, UserAccount userAccount) {
if (cache.containsKey(userId)) {
var old = cache.get(userId);
old.userAccount = userAccount;
@ -176,43 +127,25 @@ public class LruCache {
}
}
/**
* Check if Cache contains the userId.
*
* @param userId {@link String}
* @return boolean
*/
public boolean contains(final String userId) {
public boolean contains(String userId) {
return cache.containsKey(userId);
}
/**
* Invalidate cache for user.
*
* @param userId {@link String}
*/
public void invalidate(final String userId) {
public void invalidate(String userId) {
var toBeRemoved = cache.remove(userId);
if (toBeRemoved != null) {
LOGGER.info("# {} has been updated! "
+ "Removing older version from cache...", userId);
LOGGER.info("# {} has been updated! Removing older version from cache...", userId);
remove(toBeRemoved);
}
}
/**
* Check if the cache is full.
* @return boolean
*/
public boolean isFull() {
return cache.size() >= capacity;
}
/**
* Get LRU data.
*
* @return {@link UserAccount}
*/
public UserAccount getLruData() {
return end.userAccount;
}
@ -228,8 +161,6 @@ public class LruCache {
/**
* Returns cache data in list form.
*
* @return {@link List}
*/
public List<UserAccount> getCacheDataInListForm() {
var listOfCacheData = new ArrayList<UserAccount>();
@ -243,14 +174,10 @@ public class LruCache {
/**
* Set cache capacity.
*
* @param newCapacity int
*/
public void setCapacity(final int newCapacity) {
public void setCapacity(int newCapacity) {
if (capacity > newCapacity) {
// Behavior can be modified to accommodate
// for decrease in cache size. For now, we'll
clear();
clear(); // Behavior can be modified to accommodate for decrease in cache size. For now, we'll
// just clear the cache.
} else {
this.capacity = newCapacity;

View File

@ -24,28 +24,19 @@
package com.iluwatar.caching;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.EqualsAndHashCode;
import lombok.Getter;
import lombok.Setter;
import lombok.ToString;
/**
* Entity class (stored in cache and DB) used in the application.
*/
@Data
@Setter
@Getter
@AllArgsConstructor
@ToString
@EqualsAndHashCode
public class UserAccount {
/**
* User Id.
*/
private String userId;
/**
* User Name.
*/
private String userName;
/**
* Additional Info.
*/
private String additionalInfo;
}

View File

@ -26,27 +26,11 @@ package com.iluwatar.caching.constants;
/**
* Constant class for defining constants.
*/
public final class CachingConstants {
/**
* User Account.
*/
public class CachingConstants {
public static final String USER_ACCOUNT = "user_accounts";
/**
* User ID.
*/
public static final String USER_ID = "userID";
/**
* User Name.
*/
public static final String USER_NAME = "userName";
/**
* Additional Info.
*/
public static final String ADD_INFO = "additionalInfo";
/**
* Constructor.
*/
private CachingConstants() {
}
}

View File

@ -1,4 +0,0 @@
/**
* Constants.
*/
package com.iluwatar.caching.constants;

View File

@ -1,52 +0,0 @@
package com.iluwatar.caching.database;
import com.iluwatar.caching.UserAccount;
/**
* <p>DBManager handles the communication with the underlying data store i.e.
* Database. It contains the implemented methods for querying, inserting,
* and updating data. MongoDB was used as the database for the application.</p>
*/
public interface DbManager {
/**
* Connect to DB.
*/
void connect();
/**
* Disconnect from DB.
*/
void disconnect();
/**
* Read from DB.
*
* @param userId {@link String}
* @return {@link UserAccount}
*/
UserAccount readFromDb(String userId);
/**
* Write to DB.
*
* @param userAccount {@link UserAccount}
* @return {@link UserAccount}
*/
UserAccount writeToDb(UserAccount userAccount);
/**
* Update record.
*
* @param userAccount {@link UserAccount}
* @return {@link UserAccount}
*/
UserAccount updateDb(UserAccount userAccount);
/**
* Update record or Insert if not exists.
*
* @param userAccount {@link UserAccount}
* @return {@link UserAccount}
*/
UserAccount upsertDb(UserAccount userAccount);
}

View File

@ -1,25 +0,0 @@
package com.iluwatar.caching.database;
/**
* Creates the database connection accroding the input parameter.
*/
public final class DbManagerFactory {
/**
* Private constructor.
*/
private DbManagerFactory() {
}
/**
* Init database.
*
* @param isMongo boolean
* @return {@link DbManager}
*/
public static DbManager initDb(final boolean isMongo) {
if (isMongo) {
return new MongoDb();
}
return new VirtualDb();
}
}

View File

@ -1,128 +0,0 @@
package com.iluwatar.caching.database;
import static com.iluwatar.caching.constants.CachingConstants.ADD_INFO;
import static com.iluwatar.caching.constants.CachingConstants.USER_ACCOUNT;
import static com.iluwatar.caching.constants.CachingConstants.USER_ID;
import static com.iluwatar.caching.constants.CachingConstants.USER_NAME;
import com.iluwatar.caching.UserAccount;
import com.iluwatar.caching.constants.CachingConstants;
import com.mongodb.MongoClient;
import com.mongodb.MongoClientOptions;
import com.mongodb.MongoCredential;
import com.mongodb.ServerAddress;
import com.mongodb.client.MongoDatabase;
import com.mongodb.client.model.UpdateOptions;
import java.util.List;
import lombok.extern.slf4j.Slf4j;
import org.bson.Document;
/**
* Implementation of DatabaseManager.
* implements base methods to work with MongoDb.
*/
@Slf4j
public class MongoDb implements DbManager {
private static final String DATABASE_NAME = "admin";
private static final String MONGO_USER = "root";
private static final String MONGO_PASSWORD = "rootpassword";
private MongoClient client;
private MongoDatabase db;
/**
* Connect to Db. Check th connection
*/
@Override
public void connect() {
MongoCredential mongoCredential = MongoCredential.createCredential(MONGO_USER,
DATABASE_NAME,
MONGO_PASSWORD.toCharArray());
MongoClientOptions options = MongoClientOptions.builder().build();
client = new MongoClient(new ServerAddress(), List.of(mongoCredential), options);
db = client.getDatabase(DATABASE_NAME);
}
@Override
public void disconnect() {
client.close();
}
/**
* Read data from DB.
*
* @param userId {@link String}
* @return {@link UserAccount}
*/
@Override
public UserAccount readFromDb(final String userId) {
var iterable = db
.getCollection(CachingConstants.USER_ACCOUNT)
.find(new Document(USER_ID, userId));
if (iterable.first() == null) {
return null;
}
Document doc = iterable.first();
if (doc != null) {
String userName = doc.getString(USER_NAME);
String appInfo = doc.getString(ADD_INFO);
return new UserAccount(userId, userName, appInfo);
} else {
return null;
}
}
/**
* Write data to DB.
*
* @param userAccount {@link UserAccount}
* @return {@link UserAccount}
*/
@Override
public UserAccount writeToDb(final UserAccount userAccount) {
db.getCollection(USER_ACCOUNT).insertOne(
new Document(USER_ID, userAccount.getUserId())
.append(USER_NAME, userAccount.getUserName())
.append(ADD_INFO, userAccount.getAdditionalInfo())
);
return userAccount;
}
/**
* Update DB.
*
* @param userAccount {@link UserAccount}
* @return {@link UserAccount}
*/
@Override
public UserAccount updateDb(final UserAccount userAccount) {
Document id = new Document(USER_ID, userAccount.getUserId());
Document dataSet = new Document(USER_NAME, userAccount.getUserName())
.append(ADD_INFO, userAccount.getAdditionalInfo());
db.getCollection(CachingConstants.USER_ACCOUNT)
.updateOne(id, new Document("$set", dataSet));
return userAccount;
}
/**
* Update data if exists.
*
* @param userAccount {@link UserAccount}
* @return {@link UserAccount}
*/
@Override
public UserAccount upsertDb(final UserAccount userAccount) {
String userId = userAccount.getUserId();
String userName = userAccount.getUserName();
String additionalInfo = userAccount.getAdditionalInfo();
db.getCollection(CachingConstants.USER_ACCOUNT).updateOne(
new Document(USER_ID, userId),
new Document("$set",
new Document(USER_ID, userId)
.append(USER_NAME, userName)
.append(ADD_INFO, additionalInfo)
),
new UpdateOptions().upsert(true)
);
return userAccount;
}
}

View File

@ -1,78 +0,0 @@
package com.iluwatar.caching.database;
import com.iluwatar.caching.UserAccount;
import java.util.HashMap;
import java.util.Map;
/**
* Implementation of DatabaseManager.
* implements base methods to work with hashMap as database.
*/
public class VirtualDb implements DbManager {
/**
* Virtual DataBase.
*/
private Map<String, UserAccount> db;
/**
* Creates new HashMap.
*/
@Override
public void connect() {
db = new HashMap<>();
}
@Override
public void disconnect() {
db = null;
}
/**
* Read from Db.
*
* @param userId {@link String}
* @return {@link UserAccount}
*/
@Override
public UserAccount readFromDb(final String userId) {
if (db.containsKey(userId)) {
return db.get(userId);
}
return null;
}
/**
* Write to DB.
*
* @param userAccount {@link UserAccount}
* @return {@link UserAccount}
*/
@Override
public UserAccount writeToDb(final UserAccount userAccount) {
db.put(userAccount.getUserId(), userAccount);
return userAccount;
}
/**
* Update reecord in DB.
*
* @param userAccount {@link UserAccount}
* @return {@link UserAccount}
*/
@Override
public UserAccount updateDb(final UserAccount userAccount) {
return writeToDb(userAccount);
}
/**
* Update.
*
* @param userAccount {@link UserAccount}
* @return {@link UserAccount}
*/
@Override
public UserAccount upsertDb(final UserAccount userAccount) {
return updateDb(userAccount);
}
}

View File

@ -1,4 +0,0 @@
/**
* Database classes.
*/
package com.iluwatar.caching.database;

View File

@ -1,20 +0,0 @@
/**
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.caching;

View File

@ -25,21 +25,25 @@ package com.iluwatar.caching;
import org.junit.jupiter.api.Test;
import java.io.IOException;
import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
/**
* Tests that Caching example runs without errors.
*/
class AppTest {
/**
* Issue: Add at least one assertion to this test case.
* <p>
*
* Solution: Inserted assertion to check whether the execution of the main method in {@link App}
* throws an exception.
*/
@Test
void shouldExecuteApplicationWithoutException() {
assertDoesNotThrow(() -> App.main(new String[]{}));
}
}

View File

@ -23,11 +23,11 @@
package com.iluwatar.caching;
import static org.junit.jupiter.api.Assertions.assertNotNull;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertNotNull;
/**
* Application test
*/
@ -43,30 +43,32 @@ class CachingTest {
// to avoid Maven compilation errors. Set flag to true to run the
// tests with MongoDB (provided that MongoDB is installed and socket
// connection is open).
app = new App(false);
AppManager.initDb(false);
AppManager.initCacheCapacity(3);
app = new App();
}
@Test
void testReadAndWriteThroughStrategy() {
assertNotNull(app);
assertNotNull(app);
app.useReadAndWriteThroughStrategy();
}
@Test
void testReadThroughAndWriteAroundStrategy() {
assertNotNull(app);
assertNotNull(app);
app.useReadThroughAndWriteAroundStrategy();
}
@Test
void testReadThroughAndWriteBehindStrategy() {
assertNotNull(app);
assertNotNull(app);
app.useReadThroughAndWriteBehindStrategy();
}
@Test
void testCacheAsideStrategy() {
assertNotNull(app);
assertNotNull(app);
app.useCacheAsideStategy();
}
}

View File

@ -1,83 +0,0 @@
package com.iluwatar.caching.database;
import com.iluwatar.caching.UserAccount;
import com.iluwatar.caching.constants.CachingConstants;
import com.mongodb.client.FindIterable;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoDatabase;
import org.bson.Document;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.mockito.Mock;
import org.mockito.internal.util.reflection.Whitebox;
import static com.iluwatar.caching.constants.CachingConstants.ADD_INFO;
import static com.iluwatar.caching.constants.CachingConstants.USER_ID;
import static com.iluwatar.caching.constants.CachingConstants.USER_NAME;
import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.mockito.Mockito.*;
class MongoDbTest {
private static final String ID = "123";
private static final String NAME = "Some user";
private static final String ADDITIONAL_INFO = "Some app Info";
@Mock
MongoDatabase db;
private MongoDb mongoDb = new MongoDb();
private UserAccount userAccount;
@BeforeEach
void init() {
db = mock(MongoDatabase.class);
Whitebox.setInternalState(mongoDb, "db", db);
userAccount = new UserAccount(ID, NAME, ADDITIONAL_INFO);
}
@Test
void connect() {
assertDoesNotThrow(() -> mongoDb.connect());
}
@Test
void readFromDb() {
Document document = new Document(USER_ID, ID)
.append(USER_NAME, NAME)
.append(ADD_INFO, ADDITIONAL_INFO);
MongoCollection<Document> mongoCollection = mock(MongoCollection.class);
when(db.getCollection(CachingConstants.USER_ACCOUNT)).thenReturn(mongoCollection);
FindIterable<Document> findIterable = mock(FindIterable.class);
when(mongoCollection.find(any(Document.class))).thenReturn(findIterable);
when(findIterable.first()).thenReturn(document);
assertEquals(mongoDb.readFromDb(ID),userAccount);
}
@Test
void writeToDb() {
MongoCollection<Document> mongoCollection = mock(MongoCollection.class);
when(db.getCollection(CachingConstants.USER_ACCOUNT)).thenReturn(mongoCollection);
doNothing().when(mongoCollection).insertOne(any(Document.class));
assertDoesNotThrow(()-> {mongoDb.writeToDb(userAccount);});
}
@Test
void updateDb() {
MongoCollection<Document> mongoCollection = mock(MongoCollection.class);
when(db.getCollection(CachingConstants.USER_ACCOUNT)).thenReturn(mongoCollection);
assertDoesNotThrow(()-> {mongoDb.updateDb(userAccount);});
}
@Test
void upsertDb() {
MongoCollection<Document> mongoCollection = mock(MongoCollection.class);
when(db.getCollection(CachingConstants.USER_ACCOUNT)).thenReturn(mongoCollection);
assertDoesNotThrow(()-> {mongoDb.upsertDb(userAccount);});
}
}

View File

@ -1,4 +1,4 @@
<?xml version="1.0" encoding="UTF-8"?>
<?xml version="1.0"?>
<!--
The MIT License
@ -23,12 +23,13 @@
THE SOFTWARE.
-->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.iluwatar</groupId>
<artifactId>java-design-patterns</artifactId>
<version>1.26.0-SNAPSHOT</version>
<version>1.25.0-SNAPSHOT</version>
</parent>
<artifactId>callback</artifactId>
<dependencies>

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@ -1,8 +1,8 @@
---
layout: pattern
title: Chain of responsibility
folder: chain-of-responsibility
permalink: /patterns/chain-of-responsibility/
folder: chain
permalink: /patterns/chain/
categories: Behavioral
language: en
tags:
@ -10,17 +10,16 @@ tags:
---
## Intent
Avoid coupling the sender of a request to its receiver by giving more than one object a chance to
handle the request. Chain the receiving objects and pass the request along the chain until an object
handles it.
## Explanation
Real-world example
Real world example
> The Orc King gives loud orders to his army. The closest one to react is the commander, then
> an officer, and then a soldier. The commander, officer, and soldier form a chain of responsibility.
> officer and then soldier. The commander, officer and soldier here form a chain of responsibility.
In plain words
@ -36,7 +35,7 @@ Wikipedia says
**Programmatic Example**
Translating our example with the orcs from above. First, we have the `Request` class:
Translating our example with the orcs from above. First we have the `Request` class:
```java
public class Request {
@ -67,7 +66,7 @@ public enum RequestType {
}
```
Next, we show the request handler hierarchy.
Then the request handler hierarchy
```java
@Slf4j
@ -117,7 +116,7 @@ public class OrcCommander extends RequestHandler {
```
The Orc King gives the orders and forms the chain.
Then we have the Orc King who gives the orders and forms the chain
```java
public class OrcKing {
@ -137,26 +136,18 @@ public class OrcKing {
}
```
The chain of responsibility in action.
Then it is used as follows
```java
var king = new OrcKing();
king.makeRequest(new Request(RequestType.DEFEND_CASTLE, "defend castle"));
king.makeRequest(new Request(RequestType.TORTURE_PRISONER, "torture prisoner"));
king.makeRequest(new Request(RequestType.COLLECT_TAX, "collect tax"));
```
The console output.
```
Orc commander handling request "defend castle"
Orc officer handling request "torture prisoner"
Orc soldier handling request "collect tax"
king.makeRequest(new Request(RequestType.DEFEND_CASTLE, "defend castle")); // Orc commander handling request "defend castle"
king.makeRequest(new Request(RequestType.TORTURE_PRISONER, "torture prisoner")); // Orc officer handling request "torture prisoner"
king.makeRequest(new Request(RequestType.COLLECT_TAX, "collect tax")); // Orc soldier handling request "collect tax"
```
## Class diagram
![alt text](./etc/chain-of-responsibility.urm.png "Chain of Responsibility class diagram")
![alt text](./etc/chain.urm.png "Chain of Responsibility class diagram")
## Applicability
@ -166,7 +157,7 @@ Use Chain of Responsibility when
* You want to issue a request to one of several objects without specifying the receiver explicitly.
* The set of objects that can handle a request should be specified dynamically.
## Known uses
## Real world examples
* [java.util.logging.Logger#log()](http://docs.oracle.com/javase/8/docs/api/java/util/logging/Logger.html#log%28java.util.logging.Level,%20java.lang.String%29)
* [Apache Commons Chain](https://commons.apache.org/proper/commons-chain/index.html)

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@ -1,4 +1,4 @@
<?xml version="1.0" encoding="UTF-8"?>
<?xml version="1.0"?>
<!--
The MIT License
@ -23,14 +23,15 @@
THE SOFTWARE.
-->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.iluwatar</groupId>
<artifactId>java-design-patterns</artifactId>
<version>1.26.0-SNAPSHOT</version>
<version>1.25.0-SNAPSHOT</version>
</parent>
<artifactId>chain-of-responsibility</artifactId>
<artifactId>chain</artifactId>
<dependencies>
<dependency>
<groupId>org.junit.jupiter</groupId>

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@ -23,10 +23,11 @@
THE SOFTWARE.
-->
<!DOCTYPE suppressions PUBLIC "-//Puppy Crawl//DTD Suppressions 1.1//EN" "http://www.puppycrawl.com/dtds/suppressions_1_1.dtd">
<!DOCTYPE suppressions PUBLIC "-//Puppy Crawl//DTD Suppressions 1.1//EN"
"http://www.puppycrawl.com/dtds/suppressions_1_1.dtd">
<suppressions>
<suppress checks="AvoidStarImport" files="[\\/]src[\\/]test[\\/]java[\\/]" />
<suppress checks="[a-zA-Z0-9]*" files="[\\/]src[\\/]test[\\/]resources[\\/]" />
<suppress checks="[a-zA-Z0-9]*" files="[\\/]build[\\/]generated-sources[\\/]" />
<suppress checks="[a-zA-Z0-9]*" files="[\\/]src[\\/]main[\\/]resources[\\/]" />
<suppress checks="AvoidStarImport" files="[\\/]src[\\/]test[\\/]java[\\/]"/>
<suppress checks="[a-zA-Z0-9]*" files="[\\/]src[\\/]test[\\/]resources[\\/]"/>
<suppress checks="[a-zA-Z0-9]*" files="[\\/]build[\\/]generated-sources[\\/]"/>
<suppress checks="[a-zA-Z0-9]*" files="[\\/]src[\\/]main[\\/]resources[\\/]"/>
</suppressions>

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@ -1,4 +1,3 @@
<?xml version="1.0" encoding="UTF-8"?>
<!--
The MIT License
@ -24,21 +23,21 @@
-->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.iluwatar</groupId>
<artifactId>java-design-patterns</artifactId>
<version>1.26.0-SNAPSHOT</version>
</parent>
<artifactId>circuit-breaker</artifactId>
<dependencies>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.iluwatar</groupId>
<artifactId>java-design-patterns</artifactId>
<version>1.25.0-SNAPSHOT</version>
</parent>
<artifactId>circuit-breaker</artifactId>
<dependencies>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>

View File

@ -1,38 +0,0 @@
# Build output
target/
*.class
# Log file
*.log
# BlueJ files
*.ctxt
# Mobile Tools for Java (J2ME)
.mtj.tmp/
# Package Files #
*.jar
*.war
*.ear
*.zip
*.tar.gz
*.rar
# virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
hs_err_pid*
# IDE
.idea/
*.iml
.settings/
.project
.classpath
# macOS
.DS_Store
# Azure Functions
local.settings.json
bin/
obj/

View File

@ -1,83 +0,0 @@
---
layout: pattern
title: Claim Check Pattern
folder: cloud-claim-check-pattern
permalink: /patterns/cloud-claim-check-pattern/
categories: Cloud
language: en
tags:
- Cloud distributed
- Microservices
---
## Name
[Claim Check Pattern](https://docs.microsoft.com/en-us/azure/architecture/patterns/claim-check)
## Also known as
[Reference-Based Messaging](https://www.enterpriseintegrationpatterns.com/patterns/messaging/StoreInLibrary.html)
## Intent
- Reduce the load of data transfer through the Internet. Instead of sending actual data directly, just send the message reference.
- Improve data security. As only message reference is shared, no data is exposed to the Internet.
## Explanation
Real-World Example
> Suppose if you want to build a photo processing system. A photo processing system takes an image as input, processes it, and outputs a different set of images. Consider system has one persistent storage, one input component, ten processing components, messaging platform. Once a photo is given to the input component, it stores that image on persistent storage. It then creates ten different messages/events with the same image location and publishes them to the messaging platform. The messaging platform triggers ten different processing components. The ten processing components extract information about image location from the received event and then read an image from persistent storage. They generate ten different images from the original image and drop these images again to persistent storage.
In Plain words
> Split a large message into a claim check and a payload. Send the claim check to the messaging platform and store the payload to an external service. This pattern allows large messages to be processed while protecting the message bus and the client from being overwhelmed or slowed down. This pattern also helps to reduce costs, as storage is usually cheaper than resource units used by the messaging platform.([ref](https://docs.microsoft.com/en-us/azure/architecture/patterns/claim-check))
## Architecture Diagram
![alt text](./etc/Claim-Check-Pattern.png "Claim Check Pattern")
## Applicability
Use the Claim Check Pattern when
- Huge processing data causes a lot of bandwidth consumption to transfer data through the Internet.
- To secure your data transfer by storing in common persistent storage.
- Using a cloud platform - Azure Functions or AWS Lambda, Azure EventGrid or AWS Event Bridge, Azure Blob Storage or AWS S3 Bucket.
- Each service must be independent and idempotent. Output data is dropped to persistent storage by the service.
- Publish-subscribe messaging pattern needs to be used.
## Consequences
- This pattern is stateless. Any compute API will not store any data.
- You must have persistent storage and a reliable messaging platform.
## Tutorials
### Workflow
Suppose a telecom company wants to build call cost calculator system which generate the call cost daily. At the end of each day, details of the calls made by the consumers are stored somewhere. The call calculator system will read this data and generate call cost data for each user. Consumers will be billed using this generated data in case of postpaid service.
Producer class( `UsageDetailPublisherFunction` Azure Function) will generate call usage details (here we are generating call data in producer class itself. In real world scenario, it will read from storage). `UsageDetailPublisherFunction` creates a message. Message consists of message header and message body. Message header is basically an event grid event or claim or message reference. Message body contains actual data. `UsageDetailPublisherFunction` sends a message header to Event Grid topic `usage-detail` and drops an entire message to the blob storage. Event Grid then sent this message header to the `UsageCostProcessorFunction` Azure function. It will read the entire message from blob storage with the help of the header, will calculate call cost and drop the result to the blob storage.
### Class Diagrams
![alt text](./etc/class-diagram.png "Claim-Check-Class-Diagram")
### Setup
- Any operating system can be used macOS, Windows, Linux as everything is deployed on Azure.
- Install Java JDK 11 and set up Java environmental variables.
- Install Git.
- Install Visual Studio Code.
- Install [ Azure Functions extension](https://marketplace.visualstudio.com/items?itemName=ms-azuretools.vscode-azurefunctions) to be able to deploy using Visual studio.
### Storage Data
The data is stored in the Azure blob storage in the container `callusageapp`. For every trigger, one GUID is created. Under the `GUID folder`, 2 files will be created `input.json` and `output.json`.
`Input.json` is dropped `producer` azure function which contains call usage details.` Output.json` contains call cost details which are dropped by the `consumer` azure function.
## Credits
- [Messaging Pattern - Claim Check](https://www.enterpriseintegrationpatterns.com/patterns/messaging/StoreInLibrary.html)
- [Azure Architecture Pattern - Claim Check Pattern](https://docs.microsoft.com/en-us/azure/architecture/patterns/claim-check)

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@ -1,38 +0,0 @@
# Build output
target/
*.class
# Log file
*.log
# BlueJ files
*.ctxt
# Mobile Tools for Java (J2ME)
.mtj.tmp/
# Package Files #
*.jar
*.war
*.ear
*.zip
*.tar.gz
*.rar
# virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
hs_err_pid*
# IDE
.idea/
*.iml
.settings/
.project
.classpath
# macOS
.DS_Store
# Azure Functions
local.settings.json
bin/
obj/

View File

@ -1,117 +0,0 @@
@startuml
package com.iluwatar.claimcheckpattern.producer.calldetails.functions {
class UsageDetailPublisherFunction {
- eventHandlerUtility : EventHandlerUtility<MessageHeader>
- messageHandlerUtility : MessageHandlerUtility<UsageDetail>
+ UsageDetailPublisherFunction()
+ UsageDetailPublisherFunction(messageHandlerUtility : MessageHandlerUtility<UsageDetail>, eventHandlerUtility : EventHandlerUtility<MessageHeader>)
+ run(request : HttpRequestMessage<Optional<String>>, context : ExecutionContext) : HttpResponseMessage
}
}
package com.iluwatar.claimcheckpattern.domain {
class Message<T> {
- messageBody : MessageBody<T>
- messageHeader : MessageHeader
+ Message<T>()
+ getMessageBody() : MessageBody<T>
+ getMessageHeader() : MessageHeader
+ setMessageBody(messageBody : MessageBody<T>)
+ setMessageHeader(messageHeader : MessageHeader)
}
class MessageBody<T> {
- data : List<T>
+ MessageBody<T>()
+ getData() : List<T>
+ setData(data : List<T>)
}
class MessageHeader {
- data : Object
- dataVersion : String
- eventTime : String
- eventType : String
- id : String
- subject : String
- topic : String
+ MessageHeader()
+ getData() : Object
+ getDataVersion() : String
+ getEventTime() : String
+ getEventType() : String
+ getId() : String
+ getSubject() : String
+ getTopic() : String
+ setData(data : Object)
+ setDataVersion(dataVersion : String)
+ setEventTime(eventTime : String)
+ setEventType(eventType : String)
+ setId(id : String)
+ setSubject(subject : String)
+ setTopic(topic : String)
}
class MessageReference {
- dataFileName : String
- dataLocation : String
+ MessageReference()
+ MessageReference(dataLocation : String, dataFileName : String)
+ getDataFileName() : String
+ getDataLocation() : String
+ setDataFileName(dataFileName : String)
+ setDataLocation(dataLocation : String)
}
class UsageCostDetail {
- callCost : double
- dataCost : double
- userId : String
+ UsageCostDetail()
+ getCallCost() : double
+ getDataCost() : double
+ getUserId() : String
+ setCallCost(callCost : double)
+ setDataCost(dataCost : double)
+ setUserId(userId : String)
}
class UsageDetail {
- data : int
- duration : int
- userId : String
+ UsageDetail()
+ getData() : int
+ getDuration() : int
+ getUserId() : String
+ setData(data : int)
+ setDuration(duration : int)
+ setUserId(userId : String)
}
}
package com.iluwatar.claimcheckpattern.utility {
class EventHandlerUtility<T> {
- customEventClient : EventGridPublisherClient<BinaryData>
+ EventHandlerUtility<T>()
+ EventHandlerUtility<T>(customEventClient : EventGridPublisherClient<BinaryData>)
+ publishEvent(customEvent : T, logger : Logger)
}
class MessageHandlerUtility<T> {
- blobServiceClient : BlobServiceClient
+ MessageHandlerUtility<T>()
+ MessageHandlerUtility<T>(blobServiceClient : BlobServiceClient)
+ dropToPersistantStorage(message : Message<T>, logger : Logger)
+ readFromPersistantStorage(messageReference : MessageReference, logger : Logger) : Message<T>
}
}
package com.iluwatar.claimcheckpattern.consumer.callcostprocessor.functions {
class UsageCostProcessorFunction {
- messageHandlerUtilityForUsageCostDetail : MessageHandlerUtility<UsageCostDetail>
- messageHandlerUtilityForUsageDetail : MessageHandlerUtility<UsageDetail>
+ UsageCostProcessorFunction()
+ UsageCostProcessorFunction(messageHandlerUtilityForUsageDetail : MessageHandlerUtility<UsageDetail>, messageHandlerUtilityForUsageCostDetail : MessageHandlerUtility<UsageCostDetail>)
- calculateUsageCostDetails(usageDetailsList : List<UsageDetail>) : List<UsageCostDetail>
+ run(request : HttpRequestMessage<Optional<String>>, context : ExecutionContext) : HttpResponseMessage
}
}
UsageCostProcessorFunction --> "-messageHandlerUtilityForUsageDetail" MessageHandlerUtility
Message --> "-messageBody" MessageBody
UsageDetailPublisherFunction --> "-eventHandlerUtility" EventHandlerUtility
Builder ..+ HttpResponseMessage
UsageDetailPublisherFunction --> "-messageHandlerUtility" MessageHandlerUtility
Message --> "-messageHeader" MessageHeader
@enduml

View File

@ -1,7 +0,0 @@
{
"version": "2.0",
"extensionBundle": {
"id": "Microsoft.Azure.Functions.ExtensionBundle",
"version": "[1.*, 2.0.0)"
}
}

View File

@ -1,150 +0,0 @@
<?xml version="1.0" encoding="UTF-8" ?>
<!--
The MIT License
Copyright © 2014-2021 Ilkka Seppälä
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
-->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.iluwatar</groupId>
<artifactId>claim-check-pattern</artifactId>
<version>1.25.0-SNAPSHOT</version>
</parent>
<artifactId>call-usage-app</artifactId>
<name>call-usage-app</name>
<packaging>jar</packaging>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<azure.functions.maven.plugin.version>1.14.0</azure.functions.maven.plugin.version>
<azure.functions.java.library.version>1.4.2</azure.functions.java.library.version>
<functionAppName>CallUsageApp</functionAppName>
</properties>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>com.azure</groupId>
<artifactId>azure-sdk-bom</artifactId>
<version>1.0.4</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<dependencies>
<dependency>
<groupId>com.microsoft.azure.functions</groupId>
<artifactId>azure-functions-java-library</artifactId>
<version>${azure.functions.java.library.version}</version>
</dependency>
<dependency>
<groupId>com.azure</groupId>
<artifactId>azure-messaging-eventgrid</artifactId>
</dependency>
<dependency>
<groupId>com.azure</groupId>
<artifactId>azure-storage-blob</artifactId>
<version>12.13.0</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-simple</artifactId>
<scope>test</scope>
</dependency>
<!-- Test -->
<dependency>
<groupId>org.mockito</groupId>
<artifactId>mockito-core</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>com.microsoft.azure</groupId>
<artifactId>azure-functions-maven-plugin</artifactId>
<version>${azure.functions.maven.plugin.version}</version>
<configuration>
<!-- function app name -->
<appName>${functionAppName}</appName>
<!-- function app resource group -->
<resourceGroup>java-functions-group</resourceGroup>
<!-- function app service plan name -->
<appServicePlanName>java-functions-app-service-plan</appServicePlanName>
<!-- function app region-->
<!-- refers https://github.com/microsoft/azure-maven-plugins/wiki/Azure-Functions:-Configuration-Details#supported-regions for all valid values -->
<region>westus</region>
<!-- function pricingTier, default to be consumption if not specified -->
<!-- refers https://github.com/microsoft/azure-maven-plugins/wiki/Azure-Functions:-Configuration-Details#supported-pricing-tiers for all valid values -->
<!-- <pricingTier></pricingTier> -->
<!-- Whether to disable application insights, default is false -->
<!-- refers https://github.com/microsoft/azure-maven-plugins/wiki/Azure-Functions:-Configuration-Details for all valid configurations for application insights-->
<!-- <disableAppInsights></disableAppInsights> -->
<runtime>
<!-- runtime os, could be windows, linux or docker-->
<os>windows</os>
<javaVersion>11</javaVersion>
</runtime>
<appSettings>
<property>
<name>FUNCTIONS_EXTENSION_VERSION</name>
<value>~3</value>
</property>
</appSettings>
</configuration>
<executions>
<execution>
<id>package-functions</id>
<goals>
<goal>package</goal>
</goals>
</execution>
</executions>
</plugin>
<!--Remove obj folder generated by .NET SDK in maven clean-->
<plugin>
<artifactId>maven-clean-plugin</artifactId>
<version>3.1.0</version>
<configuration>
<filesets>
<fileset>
<directory>obj</directory>
</fileset>
</filesets>
</configuration>
</plugin>
</plugins>
</build>
</project>

View File

@ -1,168 +0,0 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.claimcheckpattern.consumer.callcostprocessor.functions;
import com.azure.core.util.BinaryData;
import com.azure.core.util.serializer.TypeReference;
import com.azure.messaging.eventgrid.EventGridEvent;
import com.azure.messaging.eventgrid.systemevents.SubscriptionValidationEventData;
import com.azure.messaging.eventgrid.systemevents.SubscriptionValidationResponse;
import com.iluwatar.claimcheckpattern.domain.Message;
import com.iluwatar.claimcheckpattern.domain.MessageBody;
import com.iluwatar.claimcheckpattern.domain.MessageHeader;
import com.iluwatar.claimcheckpattern.domain.MessageReference;
import com.iluwatar.claimcheckpattern.domain.UsageCostDetail;
import com.iluwatar.claimcheckpattern.domain.UsageDetail;
import com.iluwatar.claimcheckpattern.utility.MessageHandlerUtility;
import com.microsoft.azure.functions.ExecutionContext;
import com.microsoft.azure.functions.HttpMethod;
import com.microsoft.azure.functions.HttpRequestMessage;
import com.microsoft.azure.functions.HttpResponseMessage;
import com.microsoft.azure.functions.HttpStatus;
import com.microsoft.azure.functions.annotation.AuthorizationLevel;
import com.microsoft.azure.functions.annotation.FunctionName;
import com.microsoft.azure.functions.annotation.HttpTrigger;
import java.time.OffsetDateTime;
import java.util.ArrayList;
import java.util.List;
import java.util.Optional;
/**
* Azure Functions with HTTP Trigger.
* This is Consumer class.
*/
public class UsageCostProcessorFunction {
private MessageHandlerUtility<UsageDetail> messageHandlerUtilityForUsageDetail;
private MessageHandlerUtility<UsageCostDetail> messageHandlerUtilityForUsageCostDetail;
public UsageCostProcessorFunction() {
this.messageHandlerUtilityForUsageDetail = new MessageHandlerUtility<>();
this.messageHandlerUtilityForUsageCostDetail = new MessageHandlerUtility<>();
}
public UsageCostProcessorFunction(
MessageHandlerUtility<UsageDetail> messageHandlerUtilityForUsageDetail,
MessageHandlerUtility<UsageCostDetail> messageHandlerUtilityForUsageCostDetail) {
this.messageHandlerUtilityForUsageDetail = messageHandlerUtilityForUsageDetail;
this.messageHandlerUtilityForUsageCostDetail = messageHandlerUtilityForUsageCostDetail;
}
/**
* Azure function which gets triggered when event grid event send event to it.
* After receiving event, it read input file from blob storage, calculate call cost details.
* It creates new message with cost details and drop message to blob storage.
* @param request represents HttpRequestMessage
* @param context represents ExecutionContext
* @return HttpResponseMessage
*/
@FunctionName("UsageCostProcessorFunction")
public HttpResponseMessage run(@HttpTrigger(name = "req", methods = { HttpMethod.GET,
HttpMethod.POST }, authLevel = AuthorizationLevel.ANONYMOUS)
HttpRequestMessage<Optional<String>> request,
final ExecutionContext context) {
try {
var eventGridEvents = EventGridEvent.fromString(request.getBody().get());
for (var eventGridEvent : eventGridEvents) {
// Handle system events
if (eventGridEvent.getEventType()
.equals("Microsoft.EventGrid.SubscriptionValidationEvent")) {
SubscriptionValidationEventData subscriptionValidationEventData = eventGridEvent.getData()
.toObject(SubscriptionValidationEventData.class);
// Handle the subscription validation event
var responseData = new SubscriptionValidationResponse();
responseData.setValidationResponse(subscriptionValidationEventData.getValidationCode());
return request.createResponseBuilder(HttpStatus.OK).body(responseData).build();
} else if (eventGridEvent.getEventType().equals("UsageDetail")) {
// Get message header and reference
var messageReference = eventGridEvent.getData()
.toObject(MessageReference.class);
// Read message from persistent storage
var message = this.messageHandlerUtilityForUsageDetail
.readFromPersistantStorage(messageReference, context.getLogger());
// Get Data and generate cost details
List<UsageDetail> usageDetailsList = BinaryData.fromObject(
message.getMessageBody().getData())
.toObject(new TypeReference<>() {
});
var usageCostDetailsList = calculateUsageCostDetails(usageDetailsList);
// Create message body
var newMessageBody = new MessageBody<UsageCostDetail>();
newMessageBody.setData(usageCostDetailsList);
// Create message header
var newMessageReference = new MessageReference("callusageapp",
eventGridEvent.getId() + "/output.json");
var newMessageHeader = new MessageHeader();
newMessageHeader.setId(eventGridEvent.getId());
newMessageHeader.setSubject("UsageCostProcessor");
newMessageHeader.setTopic("");
newMessageHeader.setEventType("UsageCostDetail");
newMessageHeader.setEventTime(OffsetDateTime.now().toString());
newMessageHeader.setData(newMessageReference);
newMessageHeader.setDataVersion("v1.0");
// Create entire message
var newMessage = new Message<UsageCostDetail>();
newMessage.setMessageHeader(newMessageHeader);
newMessage.setMessageBody(newMessageBody);
// Drop data to persistent storage
this.messageHandlerUtilityForUsageCostDetail.dropToPersistantStorage(newMessage,
context.getLogger());
context.getLogger().info("Message is dropped successfully");
return request.createResponseBuilder(HttpStatus.OK)
.body("Message is dropped successfully").build();
}
}
} catch (Exception e) {
context.getLogger().warning(e.getMessage());
}
return request.createResponseBuilder(HttpStatus.INTERNAL_SERVER_ERROR).body(null).build();
}
private List<UsageCostDetail> calculateUsageCostDetails(List<UsageDetail> usageDetailsList) {
if (usageDetailsList == null) {
return null;
}
var usageCostDetailsList = new ArrayList<UsageCostDetail>();
usageDetailsList.forEach(usageDetail -> {
var usageCostDetail = new UsageCostDetail();
usageCostDetail.setUserId(usageDetail.getUserId());
usageCostDetail.setCallCost(usageDetail.getDuration() * 0.30); // 0.30 per minute
usageCostDetail.setDataCost(usageDetail.getData() * 0.20); // 0.20 per MB
usageCostDetailsList.add(usageCostDetail);
});
return usageCostDetailsList;
}
}

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@ -1,43 +0,0 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.claimcheckpattern.domain;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
/**
* It is the message which gets dropped or read by Producer or Consumer Azure functions.
* It is stored in the json format.
* @param <T> represents UsageDetail or UsageCostDetail
*/
@Data
@NoArgsConstructor
@AllArgsConstructor
public class Message<T> {
private MessageHeader messageHeader;
private MessageBody<T> messageBody;
}

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@ -1,43 +0,0 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.claimcheckpattern.domain;
import java.util.List;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
/**
* It is message body of the message.
* It stores actual data in our case UsageCostDetail or UsageDetail.
* @param <T> represents UsageDetail or UsageCostDetail
*/
@Data
@NoArgsConstructor
@AllArgsConstructor
public class MessageBody<T> {
private List<T> data;
}

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@ -1,47 +0,0 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.claimcheckpattern.domain;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
/**
* This is message header or event which is sent to Event Grid.
* Its structure is same as Azure Event Grid Event Class.
*/
@Data
@NoArgsConstructor
@AllArgsConstructor
public class MessageHeader {
private String id;
private String subject;
private String topic;
private String eventType;
private String eventTime;
private Object data;
private String dataVersion;
}

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@ -1,45 +0,0 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.claimcheckpattern.domain;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
/**
* This is claim/message reference class.
* It contains the information about data where it is stored in persistent storage
* and file name.
* dataLocation is blob storage container name.
* dataFileName is file name in above container.
*/
@Data
@NoArgsConstructor
@AllArgsConstructor
public class MessageReference {
private String dataLocation;
private String dataFileName;
}

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@ -1,43 +0,0 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.claimcheckpattern.domain;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
/**
* This is call cost details class.
* It stores userId of the caller, call duration cost and data cost.
*/
@Data
@NoArgsConstructor
@AllArgsConstructor
public class UsageCostDetail {
private String userId;
private double callCost;
private double dataCost;
}

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@ -1,44 +0,0 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.claimcheckpattern.domain;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
/**
* This is call usage detail calls.
* It stores userId of the caller, call duration and data used.
*/
@Data
@NoArgsConstructor
@AllArgsConstructor
public class UsageDetail {
private String userId;
private int duration;
private int data;
}

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@ -1,146 +0,0 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.claimcheckpattern.producer.calldetails.functions;
import com.azure.messaging.eventgrid.EventGridEvent;
import com.azure.messaging.eventgrid.systemevents.SubscriptionValidationEventData;
import com.azure.messaging.eventgrid.systemevents.SubscriptionValidationResponse;
import com.iluwatar.claimcheckpattern.domain.Message;
import com.iluwatar.claimcheckpattern.domain.MessageBody;
import com.iluwatar.claimcheckpattern.domain.MessageHeader;
import com.iluwatar.claimcheckpattern.domain.MessageReference;
import com.iluwatar.claimcheckpattern.domain.UsageDetail;
import com.iluwatar.claimcheckpattern.utility.EventHandlerUtility;
import com.iluwatar.claimcheckpattern.utility.MessageHandlerUtility;
import com.microsoft.azure.functions.ExecutionContext;
import com.microsoft.azure.functions.HttpMethod;
import com.microsoft.azure.functions.HttpRequestMessage;
import com.microsoft.azure.functions.HttpResponseMessage;
import com.microsoft.azure.functions.HttpStatus;
import com.microsoft.azure.functions.annotation.AuthorizationLevel;
import com.microsoft.azure.functions.annotation.FunctionName;
import com.microsoft.azure.functions.annotation.HttpTrigger;
import java.time.OffsetDateTime;
import java.util.ArrayList;
import java.util.List;
import java.util.Optional;
import java.util.Random;
import java.util.UUID;
/**
* Azure Functions with HTTP Trigger.
* This is Producer class.
*/
public class UsageDetailPublisherFunction {
private MessageHandlerUtility<UsageDetail> messageHandlerUtility;
private EventHandlerUtility<MessageHeader> eventHandlerUtility;
public UsageDetailPublisherFunction() {
this.messageHandlerUtility = new MessageHandlerUtility<>();
this.eventHandlerUtility = new EventHandlerUtility<>();
}
public UsageDetailPublisherFunction(MessageHandlerUtility<UsageDetail> messageHandlerUtility,
EventHandlerUtility<MessageHeader> eventHandlerUtility) {
this.messageHandlerUtility = messageHandlerUtility;
this.eventHandlerUtility = eventHandlerUtility;
}
/**
* Azure function which create message, drop it in persistent storage
* and publish the event to Event Grid topic.
* @param request represents HttpRequestMessage
* @param context represents ExecutionContext
* @return HttpResponseMessage
*/
@FunctionName("UsageDetailPublisherFunction")
public HttpResponseMessage run(@HttpTrigger(name = "req", methods = {
HttpMethod.POST }, authLevel = AuthorizationLevel.ANONYMOUS)
HttpRequestMessage<Optional<String>> request,
final ExecutionContext context) {
try {
var eventGridEvents = EventGridEvent.fromString(request.getBody().get());
for (EventGridEvent eventGridEvent : eventGridEvents) {
// Handle system events
if (eventGridEvent.getEventType()
.equals("Microsoft.EventGrid.SubscriptionValidationEvent")) {
SubscriptionValidationEventData subscriptionValidationEventData = eventGridEvent.getData()
.toObject(SubscriptionValidationEventData.class);
// Handle the subscription validation event
var responseData = new SubscriptionValidationResponse();
responseData.setValidationResponse(subscriptionValidationEventData.getValidationCode());
return request.createResponseBuilder(HttpStatus.OK).body(responseData).build();
} else if (eventGridEvent.getEventType().equals("UsageDetail")) {
// Create message body
var messageBody = new MessageBody<UsageDetail>();
var usageDetailsList = new ArrayList<UsageDetail>();
var random = new Random();
for (int i = 0; i < 51; i++) {
var usageDetail = new UsageDetail();
usageDetail.setUserId("userId" + i);
usageDetail.setData(random.nextInt(500));
usageDetail.setDuration(random.nextInt(500));
usageDetailsList.add(usageDetail);
}
messageBody.setData(usageDetailsList);
// Create message header
var messageHeader = new MessageHeader();
messageHeader.setId(UUID.randomUUID().toString());
messageHeader.setSubject("UsageDetailPublisher");
messageHeader.setTopic("usagecostprocessorfunction-topic");
messageHeader.setEventType("UsageDetail");
messageHeader.setEventTime(OffsetDateTime.now().toString());
var messageReference = new MessageReference("callusageapp",
messageHeader.getId() + "/input.json");
messageHeader.setData(messageReference);
messageHeader.setDataVersion("v1.0");
// Create entire message
var message = new Message<UsageDetail>();
message.setMessageHeader(messageHeader);
message.setMessageBody(messageBody);
// Drop data to persistent storage
this.messageHandlerUtility.dropToPersistantStorage(message, context.getLogger());
// Publish event to event grid topic
eventHandlerUtility.publishEvent(messageHeader, context.getLogger());
context.getLogger().info("Message is dropped and event is published successfully");
return request.createResponseBuilder(HttpStatus.OK).body(message).build();
}
}
} catch (Exception e) {
context.getLogger().warning(e.getMessage());
}
return request.createResponseBuilder(HttpStatus.OK).body(null).build();
}
}

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@ -1,66 +0,0 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.claimcheckpattern.utility;
import com.azure.core.credential.AzureKeyCredential;
import com.azure.core.util.BinaryData;
import com.azure.messaging.eventgrid.EventGridPublisherClient;
import com.azure.messaging.eventgrid.EventGridPublisherClientBuilder;
import java.util.logging.Logger;
/**
* This class is event publisher utility which published message header to Event Grid topic.
* @param <T> represents UsageDetail or UsageCostDetail
*/
public class EventHandlerUtility<T> {
private EventGridPublisherClient<BinaryData> customEventClient;
/** Default constructor.
*/
public EventHandlerUtility() {
this.customEventClient = new EventGridPublisherClientBuilder()
.endpoint(System.getenv("EventGridURL"))
.credential(new AzureKeyCredential(System.getenv("EventGridKey")))
.buildCustomEventPublisherClient();
}
/**
Parameterized constructor.
*/
public EventHandlerUtility(EventGridPublisherClient<BinaryData> customEventClient) {
this.customEventClient = customEventClient;
}
/**
Method for publishing event to Event Grid Topic.
*/
public void publishEvent(T customEvent, Logger logger) {
try {
customEventClient.sendEvent(BinaryData.fromObject(customEvent));
} catch (Exception e) {
logger.info(e.getMessage());
}
}
}

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